Instrumental and laboratory diagnostics of colorectal cancer

Current medicine is available a large number of methods for the clear diagnosis of malignant bowel diseases. These methods include both instrumental and non-instrumental examination, radiography, physiological and bacteriological tests, etc.

Diagnosis of colorectal cancer is usually considered as a comprehensive examination. At the first stage, the patient takes blood for clinical and biochemical analysis, then - studies the feces.

Mandatory for many years is the finger research of the rectum - often with this procedure and the standard diagnostic scheme begins. What can the doctor give to this or that type of examination? Let's consider this issue in more detail.

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

The initial stage of the diagnosis of rectal cancer

If you suspect a cancerous tumor, some signs, such as augmentation of the abdomen, external fistulous exits, enlarged lymph nodes, are sometimes revealed during the examination. Tapping the abdomen allows you to detect the accumulation of fluid (ascites) or gases during perforation of the gut.

The palpation of the abdomen, despite its external simplicity, is considered a very valuable procedure for determining the tumor process. Thanks to palpation, you can assess the degree of muscle tension, the presence of spasms and fluids, etc. On a mandatory basis, the doctor examines all the lymph nodes that can be affected by the pathological process.

Inspection of the perineal zone allows you to see changes in the skin and anal sphincter, which can also be valuable information for diagnosing.

Finger examination of the rectum and is considered a simple but very informative procedure. It is carried out both with a preventive visit to the doctor, and in the presence of complaints related to the work of the lower intestine. If such a survey is carried out carefully and correctly, it is possible to assess the condition of most of the rectum, and even establish a preliminary diagnosis. How to proceed: in the rectum area, the doctor enters the finger and probes its walls from the inside. The study may not be very pleasant, but painless.

Analyzes for suspected colorectal cancer

What laboratory tests are usually prescribed for suspected cancer?

• Feces for the presence of hidden blood - this method determines whether there is hidden bleeding or bleeding of the tumor. In order for the result to be as true as possible, feces should be taken several times, and for prevention - once a year.
• A general blood test - helps determine if a person has anemia associated with hidden blood loss. A low level of hemoglobin can be one of the first signs of cancer.
• Biochemistry of blood - is an evaluation of carcinoembryonic antigen (SEA), the level of which determines the stage of the malignant process. Usually biochemistry is prescribed before and after surgery. As a rule, within 2 months after a radical operation, the content of SEA comes back to normal. If there are metastases or a relapse of oncology develops, then its values again increase.
• The study of feces on DNA is a specific analysis that is conducted to detect mutated genes, that is, altered cellular structures that give impetus to the formation of malignant pathology.

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

Cancer Markers for Rectal Cancer

As is known, the complexity of diagnosing a cancerous tumor is largely due to its asymptomatic course, when the patient seeks help only when the disease goes too far. For this reason, scientists have long sought a diagnostic method that would help to identify pathology as early as possible. And this method was found - this is the definition of oncomarkers.

What are they? Oncomarkers are unique protein substances that are released during the vital activity of tumor cells. They are defined in the blood or urine fluid of a patient with oncology. With the help of modern means, it is possible to determine the increase in the level of such substances even in the initial stages of cancer.

As indicated by the level of markers:

• in what organ can the neoplasm be located;
• whether the intended treatment was effective;
• whether repeated pathologies are possible;
• whether there is a risk of cancer in the future.

A number of oncomarkers are known, which indicate the presence and localization of the cancer process in the rectum. These are markers such as AFP, CA 72-4, LASA-P, CA 242, CA 19-9, CYFRA 21-1.

However, there are some shortcomings in the analysis of markers:

• oncomarkers are not strictly specific - for example, the same indicator may indicate the presence of a process in any of the digestive system;
• the high content of markers can not in all cases be interpreted as the presence of a tumor;
• in some healthy people, too, these substances can be determined.

From all of the above, we can draw the following conclusions: the definition of markers is an important procedure, but one can not establish a diagnosis on the basis of their increase alone. Diagnosis should be perceived in a complex, using all possible techniques.

[11], [12], [13], [14], [15]

Instrumental Diagnosis of Rectal Cancer

The objective of instrumental diagnostics of the rectum is the visualization of the damaged area, the definition of the nature of the lesion and its stage, the capture of the tissue element for more detailed examination (biopsy), as well as the preliminary evaluation of metastasis.

• Anoscopy is a method of examining the rectum with the help of an anoscope - a tool that is inserted through the anal sphincter and allows you to examine the internal surface of the mucosa. The depth of possible inspection is about 15 cm.
• Recto-manoscopy is performed using the apparatus of the sigmoidoscope, which is inserted into the cavity of the rectum and up to a distance of 50 cm. This technique allows the doctor to examine the mucous membranes of the intestine, with the possibility of taking tissue elements for further analysis. The procedure can not be called pleasant and completely painless, but as a diagnosis it is often simply irreplaceable.
• Fibrocolonoscopy allows you to examine the inner surface of the intestine, pinpoint the location of the lesion, take pieces of material for biopsy, and even remove small polyps. Using this method, you can assess the state of the large intestine throughout its entire length.
• Irrigoscopy provides a enema introduction into the intestine cavity of a special contrast substance that will shade the internal cavity of the intestines when viewed on X-ray images. This procedure is used mainly in elderly patients, and also if the doctor suspects several tumoral processes in the intestine.
• Intravenous urography can be prescribed as an additional method of investigation, for example, when the tumor grows into the bladder.
• Ultrasonic monitoring of the abdominal cavity is used to detect metastases. If the procedure is carried out with the accumulation of fluid (ascites), ultrasound can estimate its volume.
• The method of computed tomography is used to determine the germination of a tumor in nearby organs, to find metastases, to check the nearest lymph nodes.
• Diagnostic laparoscopy is a minimally invasive surgical procedure where the abdominal wall is pierced in several places and a special chamber is introduced through the punctures, which allows not only to see the presence of metastases in the abdominal cavity, but also to remove small objects.

Separately, I would like to focus on the method of magnetic resonance imaging, which, although not considered a priority examination, but sometimes can provide very important information to the doctor. Determining the extent of tumor growth, the selection of a therapeutic regimen, the assessment of the need and scope of a surgical operation are just the cases when this procedure is simply necessary. In addition, MRI allows you to monitor and evaluate the course of cancer treatment and determine further tactics in relation to the patient.

Rectal cancer on the MRI will be better visualized and evaluated by the doctor if you follow these recommendations:

• Before the procedure, the rectum should be cleaned - this can be done with a laxative or usual cleansing enema;
• for 1-1,5 hours before the procedure, it is necessary to empty the bladder, after which it is not allowed to drink until the end of the study;
• approximately one hour before the MRI, it is recommended to take 3 pills of drotaverine (No-shpy).

If everything is done correctly, the doctor can easily carry out the following actions:

• See the tumor itself, including its borders;
• determine the ratio of neoplasm to pelvic organs and sphincter;
• determine the condition of the pelvic muscles;
• assess the condition of the lymphatic system in the small pelvis;
• to control the effectiveness of the operation, chemotherapy or radiation, to track the disease in dynamics.

Histological and cytological studies

In order to distinguish a benign disease from a malignant one, a study such as a biopsy is used, followed by a histological analysis. Thanks to biopsy, it is possible to state with great accuracy the presence or absence of a cancerous tumor in the tissues under investigation. The diagnostic method involves the removal of a small element of the tumor tissue - the whole process is carried out with a sigmoidoscopy and does not bring any additional discomfort to the patient. The obtained piece of tissue is subjected to a histological and cytological evaluation.

In addition to sigmoidoscopy, the doctor can take the necessary material for him during laparoscopy, surgery or fibronocolonoscopy. •

Histological examination is the examination of a specimen of tissue taken by a microscopic method and can be carried out in an urgent or planned manner:

• urgent histology is carried out for about half an hour, in the case where a quick result is needed. The sample is frozen beforehand, after which it is treated with specific colorants and examined with a microscope;
• planned histology usually lasts at least 5 days. The resulting sample is covered with a special liquid and paraffin, paint over. This method of investigation is considered more complicated if we compare it with urgent histology. However, its results are more accurate and reliable.

As a rule, in order to ensure that in the future the result of histological examination was not questioned, it is carried out by at least two specialists. •

Cytological examination is an assessment of cellular tissue structures, which allows you to notice malignant changes in them. What is the difference between this and histological analysis? The fact that the cytological method involves considering not the tissue cut, but individual tumor cells.

For the implementation of cytology, the following biological material can be used:

• specimens of tissues withdrawn from biopsies from the necessary gut section;
• purulent or mucous discharge from the intestinal cavity;
• specimens of prints from mucous tissues from the necessary part of the intestine.

Only the methods listed above make it possible to state with accuracy what tumor needs to be treated: benign or malignant.

Differential diagnosis of colorectal cancer

Cancer of the rectum should be distinguished from such diseases:

• benign polyps;
• chronic ulcerative proctosigmoiditis of dysentery, amoebic and tubercular origin;
• colitis, prolapse of the rectum, nonspecific granuloma;
• syphilis, actinomycosis;
• Melanoblastoma of the anal rectum;
• tumor germination from the uterus, vagina, prostate;
• malignant carcinoid;
• hemorrhoids and anal sphincter fissures.

In order to distinguish a cancerous tumor in the rectum from polyps, an endoscopic examination is prescribed - a colonoscopy. This method allows you to see in the lumen of the intestine not only large polyps, but also ulcers of the mucosa, inflammatory elements, small flattened polyps, deformed vessels, etc. The same method can be used to differentiate cancer and proctosigmoiditis - the inflammatory process in the sigmoid and rectum.

[16], [17], [18], [19], [20], [21], [22]

How to distinguish hemorrhoids from colorectal cancer?

Sometimes the decisive role is played by some signs, by which it is possible to distinguish the tumor process from ordinary hemorrhoids.

1. If previously the patient had polyps, then there is a risk of their degeneration into a cancerous tumor.
2. Hemorrhoidal blood is released at the end of the act of defecation, in the form of bands and spots on top of the feces. When the cancer process, the blood is not on the surface, but mixed with feces.
3. If the tumor before defecation can be mucous discharge, sometimes with pus and pieces of tissue.
4. With an extensive tumor, feces are ribbon-like, and hampered defecation can be prolonged, up to several days.
5. Tumor process is accompanied by emaciation of the patients, weakness and lethargy.
6. In the presence of metastases, the disruption of the work of other organs begins.

However, in any case, a biopsy with a histological examination of the tissues is necessary to establish an accurate diagnosis. Only after this it is possible to assert with confidence about the presence or absence of a malignant process.

Diagnosis of colorectal cancer should be carried out at the slightest suspicion of its presence. It is very important to detect a malignant disease as soon as possible - this will allow the treatment to start in a timely manner, which will significantly improve the prognosis and speed up recovery.