Colon cancer

Cancer of the large intestine now occupies the third place among its other localizations.

Colon cancer accounts for 98-99% of all cancers of the intestine, mainly adenocarcinoma, less common, mucus and scirrhosis forms.

[1], [2], [3], [4], [5]

Epidemiology

In the US, colon cancer in its prevalence ranked 2 nd after malignant skin tumors. Among other malignant lesions of the large intestine, malignant tumors dominate, accounting for 95-98%, according to various authors.

Cancer of the colon varies to a large extent in different regions of the world. The lowest rates in Africa (1.6 - 5.9 cases per 100 thousand people), the average in Southern and Eastern Europe (23.6 - 33.8 cases per 100 thousand people) and the highest in Western Europe and North America (46.3 - 51.7 cases per 100 thousand people).

With the dynamics of temporal trends, there has been a decrease in the incidence rate in recent years in the US, in European countries such as Portugal, Greece, Italy and Spain. At the same time, in most developing countries, there is an increase in the incidence of these tumors in both men and women.

Cancer of the colon is twice as likely to affect men as to women. The most frequent tumor localization is sigmoid (25-30%) and, especially, rectum (about 40%), some authors point to a rather high incidence (based on their observations) of the cancer of the cecum. All other parts of the large intestine are affected more rarely by a cancerous tumor. These data differ somewhat among different authors, but insignificantly - from 3 to 6-8% (for the ascending department of the colonic, hepatic and splenic curvature, transverse collateral and its descending section).

Among the population of Africa, Asia and South America, colon cancer is much less common than in Europe and North America, which is probably due to economic problems - and still marked by a shorter life span in the above-mentioned regions (and colon cancer occurs in mostly in elderly people). It is also believed that in economically more developed countries the high incidence of colon cancer is due to a number of nutritional characteristics, as evidenced by studies of a very large number of authors (greater consumption of animal fat and meat, some preservatives of products, etc.), as well as release into the air and water by industrial enterprises of some toxic substances with a carcinogenic effect.

In explaining the differences in the incidence of colon cancer in the regions of the globe, certain differences of the bacterial flora colonizing the large intestine of different peoples are also important, due to nutrition, preferential consumption of certain foods, and this, as is well known, largely determines the nature of the intestinal flora, some species of which, perhaps, in the course of their vital activity, can release substances that have a carcinogenic effect. Apparently, the traditions of culinary processing of food from different nationalities also have significance.

At the same time, it has been established that carcinogens found in very low concentrations in some food products (aflotoxins, N-nitro compounds, polycyclic aromatic hydrocarbons, etc.), and carcinogens that may arise during the preparation of this food, the systematic use of these products usually increase the incidence of cancer of the esophagus, stomach and liver and have little effect on the increase in the incidence of colon cancer. Therefore, we can make the assumption that some species (strains) of bacteria produce in the course of their vital activity carcinogenic substances from those completely "benign", i.e., not possessing in themselves a carcinogenic effect, products of digestion of food that reach the large intestine and remain for a long time in it (before the next defecation). Indeed, some strains of bacteria are capable of producing carcinogenic and mutagenic substances (methylazoxytonol, volatile phenols, pyrrolidine, etc.) and contain the corresponding enzymes. The development of carcinogens in the colon by these microorganisms depends on the nature of nutrition; so an increase in the content of food in the bran reduces the production of carcinogens and reduces the incidence of colon cancer.

There is an assumption that in some nationalities, feeding mainly vegetative food having a large volume, evacuation of the intestine occurs as a result of this more often than in Europe and North America, as a result of this, the contact time of possible carcinogenic agents with the mucous membrane of the colon decreases, , and hence the reduction in the frequency of carcinomatous lesions of the colon.

On the other hand, there is an opinion that the appearance of colon cancer predisposes constipation. However, since colon cancer is more common in the elderly, as well as constipation, it is difficult to single out the specific effect of each of these factors on the incidence of carcinogenesis.

Cancer of the colon can occur at any age, including children and adolescents. However, most often it is found in older age groups: in 60-69 years and 70-79 years - 28 and 18% respectively. It is interesting to note that in people of the most senior age group (80-89 years and older) its frequency again sharply decreases, approaching that of young people; The reasons for this change in the incidence of cancer in elderly and senile people are unclear.

Thus, the study of the epidemiology of colon cancer and the age-specific features of its incidence does not allow us to express sufficiently clear and convincing opinions about the etiology and pathogenesis of this disease.

If you try to connect the occurrence of malignant tumors with some local changes in the affected organ, then first of all you should keep in mind chronic inflammatory processes and so-called precancerous diseases.

Against the background of ulcerative colitis in the United States, Great Britain and Scandinavian countries, the probability of developing colon cancer increases 8-30 times, and it occurs at a younger age than in the general population (an average of 20 years earlier); 5-year survival of these patients after surgery is almost 3 times lower.

Undoubtedly the significance of the hereditary factor, in particular, many cases of the appearance of colorectal cancer in offspring in families of which in the past cases of this localization of a malignant tumor have been described. In some forms of hereditary family polyposis (Gardner's syndrome, family juvenile polyposis of the large intestine), the degeneration of polyps into cancer, according to the literature, is observed with an extremely high frequency - up to 95% and higher.

From industrial hazards, the dependence of the frequency of colon cancer on asbestosis is most clearly revealed. Undoubtedly, the chronic radiation impact on the development of malignant tumors, including the colon, is also important.

A special form of colon cancer is called the so-called primary-multiple cancer (simultaneous occurrence of cancer tumors of different localization, in this case in the large intestine), which, according to different authors, occurs in about 5% of cases. Simultaneous appearance of tumor foci in several sites indirectly indicates a single cause of their origin.

Thus, despite the abundance of hypotheses, the causes and pathogenesis of colon cancer, as well as cancer in general, remain unclear, although all the above facts and assumptions can to a certain extent explain the greater incidence of cancer in some regions compared to others.

[6], [7], [8], [9], [10]

Causes of the colon cancer

Some researchers believe that colon cancer "occurs only on pathologically altered mucosal tissue - due to inflammatory, erosive-ulcerative, scarring processes, which leads to a pathological reaction of the epithelium and promotes the appearance of the tumor."

It has been established that adenomas of the large intestine can cause cancer. A number of authors note an interesting dependence: the larger the size of the adenoma, the greater the probability of its malignancy; the most dangerous is the malignization of the so-called villous adenomas.

[11], [12], [13],

Risk factors

Dietary factors play an important role in the development of colon cancer, especially the consumption of animal fat, the absence of plant fibers in food, and a passive lifestyle. As a result, a small amount of chyme (which reflexively reduces motor activity of the intestine) enters the large intestine with a high content of bile, fatty acids, neutral fats. These changes in the chemical composition of intestinal contents slowly moving along the intestines and contacting the mucous membrane for a long time, in addition to direct irritating action, also cause disorders and microflora, which in turn changes the composition of microbial enzymes (beta-glucuronidase, alpha-dehydroxydase, etc.). With these changes in general, and associated increase in the incidence of functional, inflammatory and, most importantly, neo-educational processes in the large intestine.

Recently, it is believed that some substances have protective properties against carcinogenesis in the large intestine.

These include: ascorbic acid, selenium, vitamins A, beta-carotene, vitamin E.

Hereditary factors also play an important role in the development of approximately 20% of cases of colorectal cancer, increasing by 2-3 times the risk of its occurrence in blood relatives.

Ulcerative colitis is an established risk factor for the development of colorectal cancer. With a disease duration of more than 20 years and a lesion of the entire colon, the likelihood of a tumor is increased to 24%.

Pre-cancerous conditions include polyps, diffuse colonic colon polypsis, Gardner's syndrome, Peitz-Jigers syndrome, Türk, Cronkite-Canada, family juvenile polyposis, as well as villous adenomas, diverticulosis, Crohn's disease, pararectal fistulas (1% of cases), chronic untreated cracks in the rectum.

The frequency of detection of adenomatous polyps of the colon varies from 1.6 to 12%. With full colonoscopy, polyps and villous tumors are found in 20-50% of people over 50 years of age, and the older the age group, the greater the percentage of detection. It is generally accepted that solitary adenomatous polyps are a facultative precancerous disease, and diffuse adenomatosis is an obligatory precancer.

There is a slow development of polyps from the simplest structure to various degrees of atypia and mucosal dysplasia until the development of cancer (in 70% of cases). This process takes at least 5 years, and on average lasts 10-15 years. The malignancy index for single polyps is 1: 35, for multiple polyps - 1: 3.

The nasal tumors are exophytic formations of round or oblong form, having a characteristic velvety surface. This is due to the abundance of villi. As a rule, a villous tumor can be single. Isolate nodular and creeping forms of villous tumors. The node tumor is located on a wide base, sometimes turning into a leg. The collapsing form does not have a single tumor node.

Diffuse polyposis appears even at prepubertal age, but the full development cycle ends in 20-25 years, and up to 40 years of age, malignancy occurs in 100% of cases. Hereditary adenomatosis of the large intestine has a high potential for malignancy. In untreated cases, on average, death occurs at the age of 40-42 years, i.е. Almost 25 years earlier than with conventional colorectal cancer.

The Peitz-Jigers syndrome is a total polyposis of the colon, combined with melanin pigmentation on the face skin (cheeks, near the mouth), the mucous membrane of the lips and mouth, the skin of the back surface of the fingers and small joints, around the natural openings. Colorectal cancer in this syndrome develops in about 38% of cases.

In Turk syndrome, patients with familial polyposis have medulloblastomas and glioblastomas (tumors of the central nervous system). In the clinical picture, neurological symptoms predominate and only then - the symptoms of polyposis.

For Gardner's syndrome described in 1953, a combination of adenomatous polyps of the large intestine, anomalies of the teeth, multiple osteomas of the jaws and skull, multiple soft tissue tumors (mainly of the type of fibrosis); in many patients multiple fibroids are found in mesentery of the small intestine, lipoma of the subcutaneous tissue and other areas.

External manifestations of Gardner's syndrome often precede the development of polyps in 10-20 years. Approximately 10-15 years after the appearance of colon polyps, cancer degeneration develops.

Cronkite-Canada syndrome is a non-hereditary polyposis of the gastrointestinal tract of adults, combined with hyperpigmentation of the skin, spotted vitiligo, alopecia, nail dystrophy, edema, tetany, glossitis and cataracts.

The etiology of this syndrome is unknown. Infection or immunodeficiency is presumed. The clinical picture is characterized by proteinuria, alopecia, skin pigmentation, changes in the nails of the hands and feet. Loss of albumin is associated with increased production of mucus and with numerous necrosis of polyp endings. Clinically, this is manifested by diarrhea, weight loss, abdominal pain, anorexia, weakness, periodic discharge of blood during an act of defecation, vomiting. Mortality is 60%. 15% of patients develop colorectal carcinomas.

[14], [15], [16], [17]

Pathogenesis

Most often the cancer develops in the sigmoid (50% of cases) and the blind (15% of cases) of the gut, less often in the remaining departments (ascending colon - 12%, right bend - 8%, transverse colon - 5%, left bend - 5 %, descending colon - 5% of cases).

In the rectum, the ampullar department is most often affected by cancer (73.8% of cases), less often unpopular (23.3% of cases) and anal (2.9% of cases).

Colon cancer occurs in the mucosa. The tumor extends along the intestinal wall slightly. Outside the visible faces, even with endophytic cancer, it is detected at a distance of no more than 4 - 5, usually 1 -2 cm.

After germination of all layers of the intestinal wall, the tumor process subsequently spreads to surrounding tissues and organs. To the site of the large intestine, affected by the tumor, the strand of the large epiploon, the small intestine or its mesentery can be soldered.

Following the development of inflammatory fusion, the tumor infiltrates into the organs that are soldered to the colon. Often there is also a spread of the tumor towards the mesentery of the colon. In men, most often the cancer of the rectum extends to the seminal tubercles and the prostate gland, and in women to the uterus and vagina.

A specific feature of colon cancer is the relatively long local spread of the tumor (including germination into surrounding organs and tissues) in the absence of metastasis in the regional lymph nodes, which may appear rather late.

Cancer of the colon according to the forms of macroscopic structure is divided (AM Ganichkin) into two large groups: 1) exophytic and 2) endophytic.

The following forms of colon cancer are related to exophytic:

1. Polypoid in the form of a tumor on the pedicle;
2. nodular on a broad base of mushroom-shaped, protruding into the lumen of the intestine; can ulcerate;
3. varicose-papillary in the form of cauliflower, consisting of several nodes of different sizes.

In the rectum, also a plaque-like tumor is isolated, when the flat node along the upper central part has the same dimensions as at the edges. It has a flat or even concave surface.

The following endophytic forms of colon cancer are distinguished:

1. Ulcerative in the form of a flat ulcer with distinct raised edges; can circulate the gut circularly, stenosing its lumen;
2. diffusive-infiltrative, infiltrating the entire thickness of the wall of the colon without clear boundaries, causing a narrowing of the lumen.

Exophytic forms of cancer occur more often in the right side of the colon, they are nodular, polypoid and fleecy-papillary; the tumor grows in the lumen of the intestine. Endophytic tumors are more common in the left side of the colon. They are saucer-like and diffusely infiltrative, in the latter case, they often circulate the gut circularly and narrow its lumen.

[18], [19], [20], [21], [22], [23]

Symptoms of the colon cancer

Colon cancer symptoms are diverse, they depend on the structure and location of the tumor. The initial period (the "early cancerous tumor") usually occurs asymptomatically and if found, it is mostly only in the case of a dispensary examination or with a sigmoidoscopy, a colonoscopy, an irrigoscopy or a finger examination of the intestine, undertaken for another presumed or already existing colon disease.

Somewhat later, when colon cancer is already large enough and the first signs of cancer intoxication appear and some of the symptoms that indicate the difficulty of moving the contents across the colon, there are a number of general nonspecific symptoms such as unmotivated weakness, loss of appetite, weight loss, "intestinal discomfort "(Heaviness after eating, swelling and indeterminate nature, uneven abdominal pain, rumbling, flatulence, unstable stool, etc.). In the future, the symptoms of tumor intestinal lesions become more distinct.

Cancer of the colon on the right often occurs with intestinal bleeding, hypochromic anemia, often with pain. At palpation in some cases it is possible to probe a tuberous tumor which, despite its large enough size by this time, usually does not obviate the intestine, therefore the symptoms of intestinal obstruction for this tumor localization are of little character. This is also facilitated by the liquid contents of the right half of the large intestine, which freely passes through the narrowed section.

Cancer of the large intestine on the left often forms an annular narrowing of its lumen; the tumor is less often palpable, can cause a cramping pain in the abdomen, alternating diarrhea and constipation, sometimes a picture of partial obstructive obstruction. In this case, note the limited swelling of the left half of the abdomen and visible intestinal peristalsis. In a number of cases, the fecal masses acquire a ribbon-shaped form or a kind of "sheep's stool." Pain previously occurs when the tumor is localized in the anal ring, when it is localized in the ampulla of the rectum, it appears in a later period. Tumors of the anus are accompanied by violations of defecation. Tumors of the distal part of the rectum can be easily detected by finger research.

Symptoms of colon cancer are characterized by five major syndromes:

1. syndrome of functional signs without intestinal disorders;
2. with intestinal disorders;
3. syndrome of intestinal patency;
4. syndrome of pathological discharge;
5. violations of the general condition of patients.

The first syndrome includes abdominal pain and intestinal discomfort (loss of appetite - food intake, nausea, eructations, uncomfortable mouth, vomiting, bloating and a feeling of heaviness in the epigastric region).

Abdominal pain occurs in the majority of patients (up to 90%) - the first symptoms of colon and colon cancer. Pain can be permanent, pressing, aching, sometimes have a cramping character. Rejection of intestinal contents in case of violation of the motor function of the ileocecal occlusion apparatus leads to spastic contractions of the ileum, which is clinically manifested by pain in the right iliac region.

The inflammatory process in the tumor itself and beside it can also cause pain. With the localization of pain in the area of hepatic flexure, the transverse colon should be carried out a differential diagnosis with cholecystitis, exacerbation of peptic ulcer. If pain is localized in the right iliac region, acute appendicitis should be excluded.

Initial colon cancer symptoms of colon cancer - intestinal discomfort: nausea, eructations, unpleasant mouthfeel, vomiting, periodic swelling, feeling of heaviness and fullness in the epigastric region. The above symptoms of colon cancer concentrate the attention of patients, and often doctors, on diseases of the stomach and gallbladder.

The phenomena of intestinal discomfort are explained by the neural-reflex connections of the ileocecal region with other organs of the abdominal cavity. Concomitant cancerous inflammation, as well as absorption of decay products, intestinal contents through altered colon mucosa lead to functional disorders of the stomach, duodenum and pancreas, which are expressed by the same symptoms.

To the syndrome of intestinal disorders are symptoms of colon cancer, indicating a pronounced violation of the colon: constipation, diarrhea, constipation change diarrhea, bloating and rumbling in the abdomen. The cause of intestinal disorders are violations of motor function, paresis, or, conversely, accelerated intestinal peristalsis.

Clinical signs of intestinal disorders are most often observed with left colon cancer. This is due to the fact that endophytic tumors of the left half quickly lead to narrowing of the affected area of the intestine.

Progression of the tumor process leads to a narrowing of the lumen of the intestine and a violation of intestinal patency. Since the diameter of the lumen of the right parts of the colon is almost 2 times larger than the diameter of its left divisions, the narrowing of the lumen of the intestine with cancer of the right half and the violation of intestinal patency are much slower, with the exception of the tumor of the ileocecal damp, where obstruction can occur quite early.

Therefore, intestinal obstruction complicates (in approximately 73% of cases) the cancer of the left half, and less often the cancer of the right half of the large intestine.

Complete obturation in the tumor area is rare, but signs of obstruction appear when the lumen is narrowed to 1.0 - 0.6 cm. Intestinal obstruction usually develops in advanced stages of cancer, but in some cases it leads patients to medical institutions.

Among the symptoms of colon cancer, significant importance should be given to pathological excreta. The secretion of blood, mucus and pus with mildew during defecation is the most characteristic symptom of rectal cancer, but it can be observed in colon cancer, especially its left half.

An analysis of clinical observations shows that blood in the stool can be not only in advanced stages of cancer. With exophytic cancer, blood can appear in the early stages, with endophytic forms, pathological discharges are observed less frequently. Abundant discharge in colon cancer is rare. The daily blood loss is on the average about 2 ml.

There are violations of the general condition of patients. Among the early manifestations, such symptoms of colon cancer as anemia, fever, general malaise, weakness and emaciation are at the forefront. This picture is most typical for cancer of the right half of the colon, especially the blind and ascending.

In patients with apparent well-being, general malaise, weakness, increased fatigue, and rapid fatigue appear. After this, the pallor of the skin is noticed, in the study of blood - hypochromic anemia, sometimes fever (body temperature 37.5 ° C) is the only first sign of colon cancer.

The rise in temperature (up to 39 ° C) as an initial symptom is relatively rare among the clinical signs of colon cancer and is apparently caused by inflammatory-reactive foci in the circumference of the tumor, retroperitoneal tissue, regional lymph nodes, and the absorption of the decay products of the tumor.

In the opinion of the majority of clinicians, the development of anemia (hemoglobin below 90 g / l) is associated with intoxication as a result of absorption of the products of tumor disintegration and infected intestinal contents, but neural-reflex effects from the ileocecal part of the intestine that lead to disruption of the hematopoietic function can not be ruled out.

In one third of cancer patients, anemia is the only clinical sign of a malignant process. Hypochromic anemia as an independent disease can be diagnosed when clinically, radiologically and even operatively, cancer of the right half of the large intestine is excluded.

The thinning occurs when the cancer process has gone far in combination with other symptoms and has no great independent value. Among the general disorders of the patient's body in cancer should be attributed to such a symptom as the loss of plastic properties of connective tissue, which is expressed by the causal appearance of hernia of the abdominal wall.

In addition to the five groups of symptoms listed earlier, attention should be paid to the important objective symptoms of colon cancer - a palpable tumor. The presence of a palpable tumor directly indicates a pronounced clinical picture of colon cancer, but this does not mean the impossibility of radical surgical treatment. The tumor is determined by objective examination in almost every third patient, more often with cancer of the blind and ascending colon, hepatic flexure, less often in the sigmoid colon.

Attentive and purposeful detection of initial clinical manifestations allows not only to suspect, but also with an appropriate detailed examination, to recognize colon cancer in a timely manner.

The course and complications

The course of the disease is gradually progressing. There is an increase in anemia, increased ESR, fever is manifested, cancerous cachexia is progressing. Often in the feces there are an admixture of mucus, pus. Increasing, the tumor can sprout adjacent loops of the intestine, omentum and adjacent organs, while due to the reaction of the peritoneum and the appearance of adhesions, in a number of cases a conglomerate of rather large size is formed.

The life expectancy of patients without treatment is 2-4 years. Death comes from exhaustion or complications: profuse intestinal bleeding, intestinal perforation, followed by the development of peritonitis, intestinal obstruction, and the consequences of metastases.

[24], [25], [26], [27]

Stages

There are 4 stages of colon cancer:

1. A small tumor, limited by a mucous or submucosal layer;
2. a tumor that grows into the muscle layer and even into the serous membrane, but does not have proximal and distant metastases;
3. a tumor that has metastases to the regional lymph nodes;
4. a tumor that spreads to nearby organs or with multiple metastases.

More accurately reflects the diversity of the primary tumor process and metastasis international classification system TNM.

Depending on the size of the primary tumor, Tis (carcinoma in situ) and T1-T4 are distinguished. The absence or presence of metastases in regional and distant lymph nodes is designated as N0-N1 and N4 (categories N2 and N3 do not apply); absence or presence of distant metastases - as M0 and Mi. Histopathological gradation of cancer is also used (according to histological examination of biopsy specimens) - Gi, G2 and G3, which means high, medium and low degree of differentiation of cancer cells.

Oncologists use this classification in an even more detailed version.

According to a macroscopic picture, an exophytic form of cancer is distinguished (more often in the right part of the colon) and endophytic (more often in the left parts of the colon). Exophytic cancer is a tuberous tumor that sits more often on a broad base and grows in the lumen of the intestine, usually a polypoid or papillary cancer. During growth, the tumor can sometimes cause partial or complete obturation of the intestine, its surface may necrotic, leading to intestinal bleeding. Endophytic cancer spreads across the wall of the intestine, often enveloping it circularly, and towards the peritoneum. A tumor is a scirrus or ulcerous form of cancer. At a histological examination, adenocarcinoma is most often detected, much less often - solid and mucous cancer.

Metastases in the regional lymph nodes are often observed only in the late period of the disease. Remote metastases are most often found in the liver.

Cancer of the rectum is most often localized in its ampoule, there are ulcerative, papillomatous, fungoid and infiltrative forms. The histological form of colorectal cancer may also be different; adenocarcinoma, gelatinous, solid cancer, rarely squamous cell carcinoma. Increasing, the tumor sprouts into the neighboring organs: the bladder, uterus, sacrum. Metastasises the cancer of the rectum into the regional lymph nodes, spine, liver.

Colon cancer is localized in any of its departments, but most often in the rectum. In the rectum it is customary to allocate a lower non-popular section, equal to approximately 5 cm, medium-popular (5-10 cm) and upper-ampullar (10-15 cm). The second place in frequency is occupied by the sigmoid colon, the third - by the colon. In the colon, any of its three parts can be affected, but more often the tumor is located in the hepatic and splenic corners. Typically, the tumor grows at one node, but development of a multicentric cancer, usually genetically related to polyposis, is also possible.

Clinical classification of colorectal cancer by TNM (IUCN, 2003)

T - primary tumor:

Tx - insufficient data to estimate the primary tumor;

T0 - primary tumor is not detected;

Tis - intraepithelial or with mucosal invasion;

T1 - the tumor infiltrates the intestinal wall to the submucosa;

T2 - tumor infiltrates the muscular layer of the intestinal wall;

T3 - tumor infiltrates the subserous membrane or tissue of non-peritoneized areas of the colon and rectum;

T4 - the tumor sprouts the visceral peritoneum or directly spreads to neighboring organs and structures.

Regional lymph nodes are near-circulatory and near-rectum, as well as lymph nodes located along the iliac, right colonic, middle colonic, left colic, inferior mesenteric and upper rectal (hemorrhoidal), internal iliac arteries.

Nx - insufficient data for assessment of regional lymph nodes;

N0 - there are no signs of metastatic involvement of regional lymph nodes;

N1 - metastases in 1 - 3 regional lymph nodes; N2 - metastases in 4 or more regional lymph nodes. M - distant metastases:

Mx - insufficient data for the definition of distant metastases;

M0 - no signs of distant metastases; M1 - there are distant metastases.

Grouping by stages

Stage 0 - Tis N0 M0

Step I

• T1 N0 M0
• T2 N0 M0

Stage II

• ТЗ N0 М0
• T4 N0 M0

Stage III

• Any T N1 M0
• Any T N2 M0

Stage IV - Any T Any NM

Staging of the Duke (Dukes stage) J.Dukes (G.Dukes (1932)) identified four stages of colon cancer:

• A. The tumor is localized in the mucosa of the intestinal wall, not germinating other layers. This group includes polypoid, easily removable tumors with an ulcerated surface.
• B. The tumor is ulcerated, all layers of the intestinal wall grow and even fixed, however, as a rule, metastases in regional lymph nodes are not observed.
• C. A tumor of the same nature as in group "B", but with the presence of metastases in the regional lymph nodes.
• D. This group is represented by a primary tumor with metastases to distant organs.

[28], [29], [30], [31]

Clinical classification of cancers of the anal canal by TNM (MPRC, 2003)

T - primary tumor:

Tx - insufficient data to estimate the primary tumor;

T0 - primary tumor is not detected;

Tis - preinvasive carcinoma;

T1 - tumor up to 2 cm in the largest dimension;

T2 - tumor up to 5 cm in the largest dimension;

T3 - tumor more than 5 cm in the largest dimension;

T4 - a tumor of any size, sprouting adjacent organs: the vagina, urethra, bladder (the involvement of one muscular sphincter is not classified as T4). N - regional lymph nodes:

Nx - insufficient data for assessment of regional lymph nodes;

N0 - there are no signs of metastatic involvement of regional lymph nodes;

N1 - metastases in the circulatory lymph nodes;

N2 - metastases in the iliac or inguinal lymph nodes on one side;

N3 - metastases in the rectum and inguinal lymph nodes and / or in the iliac and / or inguinal on both sides.

Grouping by stages

Stage 0

• Tis N0 M0

Step I

• T1 N0 M0

Stage II

• T2 N0 M0
• ТЗ N0 М0

Stage IIIA

• T1 N1 M0
• T2 N1 M0
• TK N1 M0
• T4 N0 M0

Stage IIIB

• T4 N1 M0
• Any T N2, N3 M0

Stage IV

• Any T Any NM

[32], [33], [34], [35]

Forms

Classically, at the suggestion of AM Ganichkin (1970), six clinical forms of colon cancer are distinguished:

1. toxic-anemic, characterized by the prevalence of general disorders and progressive hypochromic anemia;
2. Enterocolitis, characterized by a symptom-complex of the dominant intestinal disorders;
3. Dyspepsia, in which functional disorders of the gastrointestinal tract predominate; Such patients are often examined with the diagnosis of gastritis, peptic ulcer, stomach cancer, chronic pancreatitis;
4. obturational, which is characteristic of the early appearance of the symptom complex of intestinal permeability;
5. pseudoinflammatory, among the initial clinical manifestations of which the symptoms of the inflammatory process in the abdominal cavity: abdominal pain, peritoneal irritation and abdominal wall tension, fever, leukocytosis and acceleration of the ESR; This symptom complex is a clinical manifestation of the inflammatory process, often associated with colon cancer;
6. tumor atypical, characterized by the presence of a palpable tumor in the abdominal cavity with a low degree of clinical symptoms of the disease.

Macroscopic shapes and growth patterns

Depending on the nature of growth, the following forms of colon cancer are distinguished:

1. exophytic - plaque-like, polypous, coarse-hummocky;
2. transitional (exo- and endophytic) - saucer-shaped cancer;
3. endophytic - endophytic-ulcerative and diffuse-infiltrative

In the right half of the large intestine and the ampullar department of the rectum, exophytic cancers are more often observed. For cancer of the left half of the large intestine and the rectosigmoidal division, endophytic growth is more characteristic.

[36], [37], [38],

Microscopic structure

According to the International Histological Classification of Intestinal Tumors (WHO No. 15, Geneva, 1981), the following colon cancers are distinguished:

1. adenocarcinoma;
2. mucinous (mucosal) adenocarcinoma;
3. cystic cell carcinoma;
4. squamous cell carcinoma;
5. glandular squamous cell carcinoma;
6. undifferentiated cancer;
7. unclassified cancer.

Adenocarcinoma accounts for more than 90% of all carcinomas in the colon and rectum. The tumor is constructed from atypical glandular epithelium, which forms various structures - tubular, acinar, papillary. At the same time, a different degree of differentiation of the cancer is possible.

The highly differentiated adenocarcinoma is characterized by histological and cytological signs of the normal initial epithelium, while the glandular structures of the tumor are of the same type, built from suction colonocytes, among which Panet and Kulchitsky cells are found. In the lumen of the glands there is a sufficient amount of secretion. Malodifferentiated adenocarcinoma is characterized by histological and cytological signs, only remotely resembling the normal epithelium - cells are extremely polymorphic, a large number of atypical mitoses are noted. Goblet cells are not detected. The glands that form these cells are also very diverse. Moderately differentiated adenocarcinoma is a cancer, in a set of histological signs occupying an intermediate position between the well and malodifferentsirovannymi tumors.

Mucous cancer is adenocarcinoma, which is characterized by pronounced mucus production. There are 2 types of this tumor. The first type - the tumor has a glandular structure, mucin is contained in the lumen of the glands, the latter resemble "lakes", filled with mucus; in addition, mucin is present in the stroma of the tumor. The second type is a tumor built of strands or groups of cells surrounded by mucus. For both types of mucocutaneous cancer, an evaluation of the degree of differentiation is necessary for the same criteria as for adenocarcinoma.

Cricoid-cell carcinoma is a tumor consisting exclusively of cricoid cells, in the cytoplasm of which the mucous contents are contained.

Squamous cell carcinoma in the colon and sigmoid colon is extremely rare. It occurs mainly in the transition zone between the rectum and anal canal. The tumor is constructed from atypical squamous cell epithelium cells, which are characterized by intercellular bridges and keratin - intracellular (non-coronary cancer) and extracellular (coronarizing cancer). Squamous squamous keratinizing cancer is an extremely rare tumor.

Iron-squamous cell carcinoma is an extremely rare variant of the tumor, represented by two components - adenocarcinoma and squamous cell carcinoma. In adenocarcinoma, small foci of squamous cell transformation are sometimes observed.

Undifferentiated cancer is a tumor built from atypical epithelial cells that do not contain mucus and do not form glands. Tumor cells are more often polymorphic, sometimes monomorphous, form strata and strands, separated by a sparse connective tissue stroma.

If the histologically detected tumor does not belong to any of the above and described categories, they speak of non-classified cancer.

The WHO classification (1981) also identifies a group of tumors in the anus and anus. In the anal canal, the following histological types of cancer are distinguished:

1. squamous cell;
2. cancer, resembling basal cell (basaloid);
3. mucoepidermoid;
4. adenocarcinoma;
5. undifferentiated;
6. unclassified.

Squamous cell carcinoma often has the structure of non-keratinizing and extremely rare - keratinizing. Cancer resembling basal cell (basaloid) is recommended to be called "cloacogenic cancer", according to morphology, it also varies depending on the degree of differentiation. Mucoepidermoid cancer is a combination of mucus, epidermoid cells and cells of an intermediate type. Adenocarcinoma in the anal canal is divided into 3 varieties: rectal type, adenocarcinoma of the rectal glands and adenocarcinoma in the rectal fistula.

To assess the degree of malignancy of colon cancer, in addition to histological type and degree of cancer differentiation, depth of invasion of the wall, cellular polymorphism, mitotic activity, lymphocytic and fibroblastic stromal reaction, and the form of tumor distribution should be taken into account.

Metastasizes colon cancer lymphogeneously into the regional lymph nodes and hematogenously into the liver. In cases of advanced cancer, sometimes hematogenous metastases are detected in the bones, lungs, adrenal glands, and the brain. However, as a rule, such localization of secondary tumor nodes is rare, and more often even in case of death, the process is limited to liver damage. In some cases, implantation metastases are possible in the form of peritoneal carcinomatosis.

International histological classification of intestinal tumors

Epithelial tumors.

1. Adenocarcinoma (75 - 80% of cases). According to the International Histological Classification of WHO, the degree of its differentiation is indicated (high-, medium-, low-differentiated).
2. Mucocutaneous adenocarcinoma (up to 10-12% of cases).
3. Cricoid-cell carcinoma (up to 3 -4%).
4. Squamous cell carcinoma (up to 2%).
5. Undifferentiated cancer.
6. Carcinoids.
7. Mixed carcinoid-adenocarcinoma.

Non-epithelial (mesenchymal tumors).

1. Gastrointestinal stromal tumor (GIST).
2. Leiomyosarcoma.
3. Angiosarcoma.
4. Kaposi's Sarcoma.
5. Melanoma.
6. Malignant lymphoma.
7. Malignant neurilemoma (Schwannoma).

Most malignant tumors of the colon have the structure of adenocarcinoma (about 90% of patients), less often mucosa adenocarcinoma (mucosal cancer), ring-cell carcinoma (mucocellular carcinoma), squamous (keratinizing and non-keratinizing) and undifferentiated cancer.

Complications and consequences

The most frequent complication is intestinal obstruction, which develops as a result of obstruction of the lumen of the intestine with a tumor. It occurs in 10-15% of patients. The development of obstructive obstruction in cancer of the left half of the colon is observed 4 to 6 times more often than with cancer of the right half. Occasionally, the intestinal obstruction can be caused by the invagination of an exophytally growing tumor, the curvature of the hinge loop, affected by the tumor.

Inflammation in surrounding tissues tissues develops in 12 - 35% of patients. At the same time, a clinical picture of an abscess or phlegmon develops. If the pathological process is localized in the caecum, it can proceed under the guise of acute appendicitis in the stage of an appendicular infiltrate.

To severe forms of the clinical course include cancerous tumors complicated by perforation of the intestinal wall (2 - 5% of cases). Tumor perforation can occur in the direction of the abdominal wall or retroperitoneal space, as well as into the free abdominal cavity; In rare cases, an indirect perforation of the tumor into the abdominal cavity occurs through the breakthrough of the abscess located around the tumor.

Prolonged retention of dense stools can lead to the formation of pressure ulcers in the intestinal wall directly above the tumor and the rupture of the wall (diastatic perforation - overflow perforation). The clinical picture of diastatic perforation is distinguished by the special severity of the flow. The increase in the clinical picture of intestinal obstruction with the sudden development of rapidly flowing peritonitis is an indicator of perforation from overgrowing of the intestine.

As the development of colon cancer spreads to neighboring organs (in 15 - 20% of cases). When the tumor grows into the pericardial tissue, the ureter and the kidney, dysuric disorders, moderate hematuria and albuminuria are attached. In the formation of the colonic-urobubic fistula, there may be pneumaturia and even fecaluria.

Germination of the retroperitoneal part of the duodenum and pancreas is clinically characterized by an increase in pain syndrome, the appearance of diarrhea, nausea, vomiting and worsening of the general condition of the patient. Internal fistulas with the germination of colon cancer are more likely to open into the small intestine, bladder and stomach, but pathological anastomoses may develop with the duodenum, gall bladder and between different parts of the colon.

With the spread of colon cancer on the stomach in patients noted a feeling of heaviness in the epigastric region, nausea, eructation, recurrent vomiting. With the germination of the uterus and its appendages there are pains in the lower abdomen, the menstrual cycle is upset, there are discharge from the vagina bloody or mucopurulent.

[39], [40], [41], [42], [43], [44]

Colon cancer metastases

Metastasis occurs lymphogenous (30% of cases), hematogenous (50% of cases) and implantation (20% of cases).

The main way of metastasizing colon cancer is lymphogenous, with lymph nodes of the first order located at the site of attachment of the mesentery to the wall of the intestine. Subsequently, the lymph nodes in the fission of the mesenteric vessels, and later the lymph nodes of the mesentery root, are affected.

The main zones of regional metastasis of cancer and rectum were identified by Miles as early as 1908. He showed that the spread of the tumor process occurs in three directions: ascending, lateral and descending.

Lymphogenous spread of colorectal cancer occurs during the upper rectal lymphatic vessels into the anorectal nodes, and then into the lymph nodes located at the base of the inferior mesenteric artery and further into the retroperitoneal paraaortal and preaortic lymph nodes. It is also possible metastasis of rectal cancer along the middle hemorrhoidal arteries to the iliac lymph nodes, and also retrograde along the lower hemorrhoidal arteries to the inguinal lymph nodes. Regional lymph nodes in cancer of the colon and rectum, according to various authors, are affected in 40 - 60% of observations.

Ascending metastasis includes the pararectal, upper rectal and lower mesenteric nodes, lateral dissemination affects the middle rectal, blocking, internal iliac and common iliac nodes, with downward proliferation of inguinal lymph nodes.

A number of regularities of metastasis of colorectal cancer are distinguished depending on the department in which the tumor is localized. It is believed that in cancer of the upper ampullar region, lymph nodes along the upper rectal, inferior mesenteric arteries and aorta are most often affected by metastases, in cases of cancer of the lower and middle ampullar regions, iliac lymph nodes and pelvic nodes, and in anal cancers - inguinal lymph nodes of the gut.

Lymphogenous metastasis is one of the reasons that the likelihood of relapse after surgery for colon cancer is very high. Therefore, in the surgery of rectal cancer, the lymph drainage system has always been considered as one of the main targets, the effect on which could improve long-term results.

[45], [46], [47]

Hematogenous metastasis

At the heart of the hematogenous spread of cancer lies the process of embolization by cancer cells of venous outflow tracts from organs afflicted with malignant tumors. The penetration of cancer cells into venous vessels occurs mainly as a result of invasion and destruction of the walls of the vessels by the tumor. As is known, the bulk of venous blood in the system of the superior and inferior mesenteric veins enters the portal and only from the distal part of the rectum flow into the lower vena cava. These anatomical features of the circulatory system of the colon explain why the cancers of this localization metastasize primarily to the liver. Synchronous metastases in the liver develop in 10-15% of patients with colon cancer. Second place in the frequency of distant metastasis is occupied by the lungs, with metastases being most often multiple. Metastases in the lungs of colon cancers are detected at autopsies of the deceased in 22.3% of observations.

Less often than in the liver and lungs, but still relatively often there is metastasis of colon cancer in the bones of the skeleton: in the sacro-lumbar spine, pelvic bones, ribs, sternum, thighs, collarbone, into the brain.

Implantation metastasis

When the entire thickness of the intestinal wall grows and the tumor exits the serosa, cancer cells can be implanted on the surface of the peritoneum, on the surface of the healthy mucosa in proximal or distal parts of the intestine, as well as surrounding organs and tissues.

Tumor cells most often adhere to the parietal or visceral peritoneum, appearing soon as characteristic prosyroid multiple eruptions on it. Bumps are dense to the touch and usually have a greyish-white color. In the abdominal cavity appears ascitic fluid, which is, as a rule, hemorrhagic.

Diagnostics of the colon cancer

Diagnosis of colon cancer performs the following main tasks:

• establishment of localization of colorectal cancer, its extent, anatomical form of growth and morphological structure;
• determination of local and long-term prevalence of the tumor process;
• Assessment of the general condition of the patient and the function of vital organs and systems.

Examination of the patient begins with a careful study of complaints, the history of the disease. In case of physical examination, attention should be paid to the color of the skin, the condition of the peripheral lymph nodes, to a greater extent inguinal. With palpation of the abdomen, a tumor-like formation can be detected, as a rule, with a large tumor size, as well as a painful infiltrate, indicating the attachment of inflammation. In depleted patients, the liver affected by metastases can be palpable.

Objective research ends with palpation of the rectum, and in women - with vaginal examination. Finger research is effective in 70% of patients. If the tumor is reached by a finger, then it is possible to determine its localization from the edge, as well as mobility with respect to surrounding structures.

Recto-manoscopy can diagnose cancer of the rectum and lower parts of the sigmoid colon, determine its extent, anatomical form of growth, and also take a biopsy to determine the morphological structure of the tumor.

X-ray examination of the colon allows one to recognize up to 90% of tumors. As a contrast agent, barium sulfate is used most often. Contrast substance can be taken through the mouth and then following its progress along the gastrointestinal tract is observed with the help of repeated X-ray studies. More often use the introduction of contrast by enemas. The technique of such an X-ray examination (irrigoscopy) consists of the following stages:

• the study of the contours of the intestine when it is filled with contrast;
• study of the mucosal relief after partial bowel evacuation;
• study after introduction into the gut of air (double contrasting).

X-ray signs of colon cancer:

• obstruction of the lumen of the gut with pronounced deformation of the contours;
• narrowing of the lumen of the intestine;
• defect filling;
• flat "niche" in the contour of the intestine;
• change in the relief of the intestinal mucosa;
• absence of peristalsis on the altered segment of the intestine;
• Stiffness of the intestinal wall;
• violation of the evacuation of contrast.

Colonoscopy is an endoscopic method of research of the large intestine. This method of diagnosis is available for tumors up to 1 cm in diameter, which are often determined by irrigoscopy. Unfortunately, it is not always possible to perform a full colonoscopy. In this regard, the entire colon should be examined both with the help of a colonoscopy and an irrigoscopy. This is of particular importance in multiple lesions of the large intestine, when the distally located tumor narrows the lumen of the intestine and does not allow the colonoscope to pass beyond the narrowing site. Thus, the above tumors are diagnosed during surgery or, worse, after it. Visual diagnostics at a colonoscopy is necessarily verified morphologically.

To evaluate the T criterion, the theoretically ideal method is endoscopic ultrasound. Ultrasonic colonoscopy is proposed as a method of refining the diagnosis of epithelial neoplasms of the large intestine, which, according to endosonographic criteria, differentiates benign and malignant tumors, determines the depth of their invasion into the intestinal wall, and determines the presence of metastases in regional lymph nodes.

With the help of ultrasound colonoscopy it is possible to obtain previously inaccessible by nature, volume and quality of diagnostic information:

• detection and evaluation based on the known endoscopic semiotics of various neoplasms of the colon, determining their nature, size, type of growth, obtaining tissue fragments for morphological study;
• determination of the absence or presence of tumor invasion (including an assessment of its depth) of the detected tumor into the thickness of the wall of the large intestine;
• determination of local prevalence of detected malignant tumors, involving in them adjacent to the affected area of the intestinal wall of organs and tissues, regional cavernous lymph nodes.

It was found that the sensitivity of ultrasound colonoscopy in the differential diagnosis of epithelial neoplasms of the colon is 96.7%, specificity 82.4%.

Correct determination of the depth of tumor invasion of the colon wall is possible in 75.4% of cases, with the best results obtained in the establishment of T3 and T4 invasion, where the diagnostic accuracy was 88.2 and 100%, respectively.

The accuracy of ultrasound colonoscopy for visualization of regional lymph nodes is 80.3%, sensitivity - 90.9%, specificity - 74.4%. In assessing the nature of visualized cecal lymph nodes by ultrasound, the diagnostic accuracy is 63.6% y

In a comparative aspect, the resolving possibility of ultrasound colonoscopy and other instrumental diagnostic methods has been studied.

According to all criteria of effectiveness evaluation, the method of ultrasound colonoscopy surpasses the routine (accuracy is higher by 9.5%, sensitivity by 8.2, specificity by 11.8%). The ultrasound colonoscopy for diagnostic efficiency is superior to the X-ray method for the study of neoplasms of the large intestine. The accuracy of ultrasound colonoscopy was higher by 6.7%, sensitivity by 20, specificity by 10%.

Thus, ultrasound colonoscopy is the most informative, non-invasive, repeatable, safe method of objective refining diagnostics of epithelial neoplasms of the colon, the diagnostic efficiency of which far exceeds that of all the routine methods of instrumental diagnostics used so far in clinical oncology.

The possibility of determining the presence of tumor germination through the intestinal wall by the method of computed tomography (CT) is very limited in comparison with EUS. Indeed, a good sensitivity of CT (82-89%) is adjacent to a low specificity (51%), mainly due to the fact that the tumor has an external edge of irregular shape surrounded by edematous periorrectal fat tissue, which causes a reassessment of stage distribution.

Nuclear magnetic resonance imaging (NMR) can not evaluate tumor infiltration of the rectum wall with high accuracy, but like CT it gives a good idea of the involvement of surrounding tissues and structures and in 81% -82% of cases predicts damage by metastases of regional lymph nodes.

Concerning the evaluation of criterion N, certain information can be obtained by EUS, CT pelvis and NMR. More specific studies, such as lymphangiography, interstitial lymphoscintigraphy (with Tc-99t of antimony trisulphide, a colloidal solution administered to a depth of 4 cm in each saddle-and-rectal fossa), rectal lymphoscintigraphy (from Tc-99t - colloidal solution of tin sulfide, introduced into the submucosa rectum using a special needle through the rectoscope) and immunolymphoscintigraphy of the rectum with monoclonal antibodies are used to improve the accuracy of diagnosis of lymph node involvement metastases.

Finally, regarding the evaluation of criterion M, it is known that synchronous liver metastases develop in 10-15% of patients with rectal cancer, manifesting pain in the right upper quadrant of the abdomen: right upper quadrant, right posterior thorax or right shoulder. Pain can be chronic or acute, caused by hemorrhage or necrosis of metastases. Liver enlargement can be diagnosed by routine clinical examination of patients who do not complain. Liver echo- tomography (ultrasound) is the first method in the diagnosis of metastases, although less accurate than CT or NMR, especially in patients with diffuse lesions of the liver parenchyma, as fibrosis and tissue scarring can mask the presence of small tumors. However, CT and NMR should not be used when there is no clear indication. Patients whose metastases in the liver are diagnosed with ultrasound should undergo preoperative transcutaneous needle biopsy in order to better plan surgical treatment.

To plan treatment and determine the prognosis of the disease, it is necessary to determine the characteristics of the biological aggressiveness of tumors with different growth rates, and, consequently, different kinetic and clinical features.

The most important here are the operative markers, such as CEA, the degree of differentiation, the indices of cell proliferation, the ploidy of DNA. The test with cancer-embryonic antigen (CEA) is useful and is the basis for monitoring the patient and helps forecasting. Indeed, there is a clear correlation between the preoperative level of CEA, the differentiation and stage of the disease. In highly differentiated tumors, CEA increased in 61% of cases, while in low-grade cases only in 3.5% of cases. In addition, CEA values correlate with the stages of the tumor process (the more neglected stage, the higher the CEA).

The degree of differentiation of tumor cells (G) is another useful preoperative parameter that can help in the biological assessment of colon tumors. Currently, four degrees of differentiation are distinguished: G1 - highly differentiated tumors; G2 - tumors of medium differentiation; G3 - low-grade tumors; G4 - undifferentiated tumors. This classification is based on the analysis of various gastopathological criteria of tumor cells, such as mitotic index, loss of nuclear polarity, nucleus size, hyperchromatism, atypia of glands and cells, pleomorphism and invasiveness. About 20% of tumors of the rectum are highly differentiated, 50% of medium differentiation, the remaining 30% are poorly differentiated and undifferentiated. It is emphasized that the degree of differentiation is clearly correlated with the presence of metastases in the lymph nodes: indeed, lymph node metastases are observed in Gl, G2 and G3-4 in 25, 50 and 80% of cases, respectively.

The histogram of flow cytometry of the colorectal cancer DNJ was performed in comparison with the tumor size, Duke staging, the degree of differentiation, the preoperative level of CEA, and the survival of the patient. In the study of diploid DNA in tumors, the prognosis was statistically worse (p = 0.017) with non-diploid DNA compared with diploid DNA, but the worst prognosis is in the presence of tetraploid DNA in tumor cells.

Screening of colonic cancer

To date, the ways and methods of early detection of cancer and precancerous diseases of the colon are being sought. The expediency of conducting preventive examinations in order to detect diseases of the large intestine is beyond doubt. However, during examinations the doctor faces a number of difficulties and, first of all, the unwillingness of a practically healthy person to undergo such procedures as rectoscopy, colonoscopy, etc. That is why it is necessary to develop an organizationally easily feasible study. This is currently the test for fecal occult blood, which was developed in the early 1960s, and since 1977 has been introduced into a wide clinical practice. This method is based on the famous guaiacol reaction, modernized by Gregor and called the "hemoculture test".

To date, the hemoccult test is the only screening test for the presence of colorectal cancer. It is simple in execution, does not require large expenses. This test is widely used in Europe and the US, as well as in South-East Asia and Japan. With the help of a hemoculture test, it is possible to reduce the death rate from colorectal cancer by 14-18%.

Screening of colorectal cancer should be carried out at least once every two years. With a positive result, each patient must perform a colonoscopy.

Since colon cancer develops primarily from polyps, which can also be detected with a hemocculant test, this method can be considered not only as a method of early detection of cancer, but also as a method of prevention. Detection and treatment of colon polyps is an important preventive measure in reducing cancer of the rectum and colon.

In the United States, another screening test is proposed for the early detection of rectal and colon cancer. The method is based on the analysis of mucus, taken from the rectum. Painted with Schiff's reagent, mucus changes its color if there is neoplasia in the colon. The method is simple, cheap, fast and does not give a large percentage of false positive and false-negative results. To the test is attached a set for its execution.

Recently, considerable interest has been caused by the development of domestic and foreign researchers, allowing the genetic screening of colorectal cancer. Colorectal cancer cells are secreted with feces, providing the potential for early detection of the disease by a non-invasive technique.

The method is based on the detection of mutant genes TP53, BAT26, K-KA5 in isolated from stool and multiplied by polymerase chain reaction (PCR) DNA from colorectal tumors. This technique is under development, but when it comes to acceptable sensitivity and specificity, as well as the cost of its prospects, it is very promising.

Recently, for the screening of colorectal cancer, a scrotal examination of tumor M2-pyruvate kinase has been proposed. This method allows detecting necrointestinal tumors in the large intestine, is characterized by high sensitivity and specificity. The results of applying this technique have not yet been described in the domestic literature.

To improve the quality of diagnostics, it is necessary to introduce screening tests into clinical practice with the subsequent application of radiological and endoscopic methods, as well as further scientific development of criteria allowing to form a high-risk group.

[48], [49], [50], [51], [52]

Differential diagnosis

Differential diagnosis of cancer of the intestine is performed with tuberculous lesions of the intestine, benign tumors, polyps and large intestine sarcoma. Sometimes, when palpation of the large intestine is determined by a rounded formation, which an inexperienced doctor is often immediately regarded as a cancerous tumor, but it often represents a simple accumulation of stool in the gut, and the next day the palpable "tumor" is not determined. If the tumor formation is palpable in the right ileal region, it can be an appendicular infiltrate.

Treatment of the colon cancer

Colon cancer is treated surgically. In chemotherapy in inoperable cases, 5-fluorouracil and fluoroufur are prescribed; the first drug in most cases gives the best result. However, the effect of chemotherapy is short-lived and is noted only in half of patients with colon cancer.

In some cases, radiotherapy is performed before or after the operation. However, the effectiveness of this treatment is not high. In neglected cases, when it is impossible to perform a radical operation (resection of the affected area) and violations of the permeability of the intestine, a palliative operation is performed, consisting in switching off the affected bowel area by imposing an anastomosis bypass or in rectal cancer by applying anus praeternaturalis. Symptomatic drug therapy in far-reaching cases is reduced to the appointment of antispasmodics, and with very severe pain - and narcotic analgesics. With bleeding and hypochromic anemia, hemostatic agents, iron preparations, blood transfusions are effective.

The treatment of colon cancer is to perform a surgical procedure.

Before surgery on the colon, patients need pre-operative preparation aimed at cleansing the intestine. In recent years, when preparing the intestine, use fortranet, dissolved in 3 liters of water. Applied also orthograde washing of the intestine by introducing a 6 -8 L isotonic solution through a probe installed in the duodenum. Less often use a slag-free diet and cleansing enemas.

Surgical treatment of colon cancer depends on the location of the tumor, the presence or absence of complications and metastases, the general condition of the patient. In the absence of complications (perforation, obstruction) and metastases, radical operations are performed - removal of the affected parts of the intestine along with the mesentery and regional lymph nodes.

In case of cancer of the right side of the colon, right-sided hemicolectomy is performed (the terminal ileum of the ileum is expelled in a length of 15-20 cm, the cecum, the ascending and right half of the transverse colon), completing the operation by imposing the ilotransversoanastomosis type end to side or side to side. With cancer of the middle third of the transverse colon, resection of the transverse colon is performed, completing it with a colo-anastomosis, end-to-end type. With left colon cancer, left-sided hemicolectomy is performed (the part of the transverse colon, the descending colon and part of the sigmoid colon is removed) with transversosigmoanastomosis. In cancer of the sigmoid colon, resection of the intestine is performed with removal of the regional lymph nodes.

In the presence of complications such as intestinal obstruction, perforation or inflammation with the development of peritonitis, perform two-stage resection of the colon with external removal of intestinal contents. Most often, from the category of such operations, the operational manual for Hartmann is implemented. The operation is proposed for the treatment of cancer of the sigmoid colon and recto-sigmoid section. The intestine is resected with a suturing of the distal portion tightly and extraction outward in the form of a proximal colostomy. Restoration of intestinal continuity is performed after a certain time in the absence of relapse or metastases.

In the presence of an unresponsive tumor or distant metastases, palliative operations are performed to prevent intestinal obstruction: palliative resections, superimposition of bypass ileotransversoanastomosis, transversosigmoanastomosis, or superimposed colostomy.

Chemotherapy after the operative treatment of colon cancer is prescribed to patients with tumor growth of the entire thickness of the intestinal wall and in the presence of metastases in the regional lymph nodes. At the advanced stage of the disease, the approaches to chemotherapy depend on the general condition of the patient and are individual. In this situation, it is aimed at improving the quality of life.

The main method of treating colorectal cancer remains surgical. Radical surgery for colorectal cancer is aimed at removing the tumor and regional lymph nodes.

Modern principles of surgical treatment of colorectal cancer are:

• removal of the affected part of the intestine in a single block with fiber and a vascular-neural bundle, with a high ligation of the vessels, retreating 10 cm above the tumor and 5 cm below the tumor for the colon and at least 2 cm for the rectum;
• total mesorectumectomy (removal of the rectum with surrounding fiber, vascular-nervous structures and lymph nodes, limited visceral fascia) should be performed in an acute way;
• to ensure the lateral border of resection in rectal cancer, removal of mesorectum without damaging the autonomic nerves of the pelvis (hypogastric, sacral nerves and pelvic plexus) is necessary. Removal of tumors of the middle and lower ampulla of the rectum should be accompanied by total mesorectumectomy, whereas in the case of cancer of the upper ampullar region it is sufficient to restrict mesorektum resection for 5 cm distal to the tumor;
• with localized cancer of the distal rectum (T1-2 N0M0) located above 2 cm from the dentate line, it is permissible to perform sphincter-preserving interventions with mandatory morphological control of the margins of resection.

Most often, rectal cancer involves abdominal perineal rectal extirpation, rectal rectal resection; abdominal anal resection of the rectum with the reduction of the sigmoid colon (or transverse colon), Hartmann's operation (obstructive resection).

The choice of the radical surgery method for rectal cancer is mainly determined by the remoteness of the tumor from the anus. When the tumor is located at a distance of less than 6 - 7 cm from the anus, resort to abdominal perineal extirpation of the rectum. The location of the tumor at a distance of more than 6 - 7 cm from the anus makes it possible to perform sphincter-saving operations (abdominal-anal resection with the reduction of the sigmoid colon).

When the tumor is located above 10-12 cm from the anus, it is expedient to perform anterior rectal resection. Transabdominal resection of the rectum and sigmoid colon with imposing a single-stemmed colostomy (Hartmann's operation, obstructive resection) is performed when the tumor is located above 10-12 cm from the anus and it is impossible to perform forward rectal resection for some reason (for example, in an emergency operation performed in connection with intestinal obstruction, when the intervention is conducted on an unprepared gut).

Palliative surgery is performed with the development of severe symptoms of intestinal obstruction and the impossibility of performing a radical operation. They consist in the imposition of a double-barrel colostomy or sigmostoma in the anterior abdominal wall in the left ileal region.

Despite numerous doubts about the justification of using laparoscopic technologies in the treatment of malignant diseases, minimally invasive methods are gradually introduced in interventions for colon cancer. It should be noted that at present, the literature contains data on a rather significant experience of performing laparoscopic anterior resections for cancer.

Preliminary experience shows that the use of laparoscopically assisted interventions on the rectum for malignant neoplasms is justified and expedient. The use of laparoscopic technologies leads to a reduction in the number of postoperative complications, a decrease in the severity of the pain syndrome, and a reduction in the need for narcotic analgesics. Laparoscopic technologies allow for the operation of the rectum with observance of all oncological principles, providing the necessary limits and volumes of resections. Some negative effect on the expected benefits of laparoscopic operations is observed when it is necessary to perform minilaparotomic incisions to remove the resected colon.

For a final judgment on the location and role of laparoscopic interventions in rectal cancer surgery, it is necessary to wait for the results of multi-center, prospective, randomized, comparative studies currently under way.

In cancer of the distal parts of the rectum stage III, i.e. When the tumor germinates all layers of the intestinal wall and grows into adipose tissue, and also when metastatic lesions of regional lymph nodes use combined treatment methods to improve long-term results. This is due to the fact that locoregional recurrence after surgical treatment of rectal cancer is 20 - 40%.

The exit of the tumor beyond the visceral fascia of the rectum is an indication for preoperative radiotherapy. When regional lymph nodes are damaged, preoperative radiotherapy should be supplemented with postoperative chemo- or radiotherapy.

At present, scientists are searching for methods that allow increasing the radiation dose delivered to the tumor and the areas of its regional metastasis while protecting healthy tissues. This method is hypoxirradiation. It was found that in conditions of hypoxia the body becomes more resistant to radiation aggression. Therefore, as a radioprotector, a hypoxic gas mixture containing 91% nitrogen and 9% oxygen (GGS-9) began to be used.

In general, preoperative intensive radiotherapy with the use of a hypoxic gas mixture (GGS-9) allows to increase by 25% the total focal dose delivered to the tumor and areas of possible regional metastasis without increasing the number and severity of general radiation reactions.

The increase in radiation doses up to the 25 Gy DOS improves the parameters of five-year survival of patients in comparison with radical surgical treatment by 16.4% (RNTS named after NN Blokhin).

Irradiation is used to influence the tumor and its direct distribution pathway, i. E. Zones of regional lymphogenous metastasis, and chemotherapy contributes to the destruction of subclinical metastases.

For the chemotherapy of colorectal cancer, the "Mayo Clinic Scheme": a combination of 5-fluorouracil and leucovarine is widely used throughout the world. This combination significantly increases the survival of patients and is most often used as a standard of care.

The emergence of new cytostatics (taxanes, gemcitabine, topoisomer I inhibitors, tirapazamine, SFT, etc.) opens the prospect for research into optimizing chemoradiotherapy.

Forecast

Five-year survival depends, first of all, on the stage of the disease, the histological structure and the form of tumor growth. The prognosis is more favorable if the operation is performed in the I-II stages of the disease, with an exophytic tumor, especially if it has a high degree of differentiation. The prognosis is less favorable in young patients, especially in anal cancer.

Five-year survival of patients with rectal cancer with regional metastases is 42.7%, while in the absence of metastases - 70.8%.

[53], [54], [55], [56]