Squamous cell carcinoma

In oncology, squamous cell carcinoma or squamous cell cancer is defined as a special histological type of malignant tumor that develops from pathologically modified cells of squamous epithelium, the tissue that forms the upper layer of the skin (epidermis), the mucous membranes of hollow and tubular organs of many systems (including respiratory, digestive, and urogenital), and the lining of pleural and peritoneal cavities.

Epidemiology

Squamous cell carcinoma is the most common malignancy of the cervix, accounting for 70-80% of its malignant neoplasms, and vaginal squamous cell tumor accounts for no more than 2% of all gynecologic cancer neoplasia.

By some estimates, 25-55% of all lung cancers are squamous cell carcinoma.

In 90% of cases of malignant tumors of the oral cavity, a neoplasm of squamous epithelial cells is detected. Among cancers of the nasal cavity and paranasal sinuses, nasopharynx, larynx and oropharynx, squamous cell carcinoma ranks sixth in the world in terms of incidence. And cutaneous squamous cell carcinoma is the second most common form of skin cancer after basal cell carcinoma.

Esophageal squamous cell cancer is one of the top ten most common cancers in the world.

Gastric squamous cell carcinoma is considered a very unusual and rare disease, as its incidence is estimated at 0.05% of all cases of malignant gastroenterological tumors in the world.

Causes of the squamous cell carcinoma

Not all causes of squamous cell carcinoma formation - like many other varieties of malignant tumors - are known today.

But it is known for sure that squamous cell carcinoma can be caused by more than half a dozen oncogenic types of human papillomavirus (HPV), which belongs to DNA viruses and introduces its genome into healthy cells, disrupting their regular cell cycle and structure. See - Cell division: the cell cycle

Thus, in almost 75% of patients, the development of squamous cell carcinoma of the cervix is etiologically associated with HPV 16 oncogenic type and HPV 18 type.

HPV type 51 can cause squamous cell carcinoma of the anus, HPV type 52 can cause squamous cell carcinoma of the rectum, and HPV types 45 and 68 can cause penile carcinoma.

As with most skin cancers, UV radiation damaging the DNA of the skin's epidermal cells (exposure to the sun or tanning lamps) is the most common cause of squamous cell carcinoma.

Risk factors

According to research, risk factors for squamous cell carcinoma formation are:

• for the skin - prolonged exposure to ultraviolet rays (especially with frequent sunburns), ionizing radiation, large keloid scars after burns and wounds;
• for lungs - smoking and exposure of respiratory organs to potentially carcinogenic substances, in particular, fumes of benzoyl chloride, perchloroethylene, ethylbenzene, phenolic compounds; dust containing asbestos, nickel and heavy metal compounds;
• for the nasopharynx - herpesvirus type 4, that is Epstein-Barr virus, which causes infectious mononucleosis;
• for the esophagus - alcohol abuse, gastroesophageal reflux disease and motility disorders, Barrett's esophagus, scarring of the esophagus after alkali burns;
• for the cervix - its severe dysplasia, squamous cell metaplasia, and sexually transmitted infections (STIs)
• for the vagina, the presence of genital warts and condylomas resulting from HPV infection, and for the penis, the same papillomavirus, STIs, and Bowen's disease.

Also, the likelihood of developing tumors of any histological type is higher in people with weakened immune systems and genetic predisposition.

Pathogenesis

The basic molecular mechanism of carcinogenesis, including the pathogenesis of squamous cell carcinoma formation, continues to be studied. It is attributed to damage or alteration (mutations) of the DNA of cells, which regulates their growth, development and apoptosis (programmed death).

epithelial tissues are known to have very high repair abilities. How? Due to the stem cells in them, which are capable of self-renewal for a long time and can differentiate (mature) into cell lines of the original tissue. They ensure maintenance of tissue homeostasis of the skin (cell replacement), its recovery after damage, and physiological regeneration of mucous membranes of any localization (from the larynx to the intestine). These epithelial stem cells retained the potential of proliferation - division with the formation of daughter cells.

For example, intestinal stem cells continuously self-renew by dividing and differentiating less specialized cells into specialized cells of the intestinal epithelium, which renews itself throughout life.

And that is why, according to oncology scientists, epithelial stem cells are directly related to carcinogenesis. The accumulation of mutations leads to their genetic "reprogramming" - with repeated uncontrolled division, exponential increase in the number of cells and transformation into abnormal - cancer stem cells of epithelial origin.

At first, they localize in a limited area, and this condition is called squamous cell carcinoma in situ. But once aggressive tumor cells begin to directly invade neighboring tissues, invasive squamous cell carcinoma is diagnosed. For example, squamous cell carcinoma of the cervix can grow directly into the wall of the uterus, and squamous cell carcinoma arising in the auricle is capable of invading the external ear canal, middle ear, and parotid salivary gland.

Degrees of differentiation of squamous cell carcinoma

Differentiation is the process by which immature progenitor cells become mature cells - with specific functions.

The degree of differentiation of any tumor describes how abnormal the tumor cells look when a biopsy specimen is examined histologically with an electron microscope.

When the tissue morphology of the carcinoma is similar to normal and the tumor cells appear to be mature, a highly differentiated squamous cell carcinoma is defined. It grows and spreads more slowly than low-differentiated (or moderately differentiated) squamous cell carcinoma, which consists of immature cells with atypical structures.

In addition, squamous cell carcinoma is classified according to another histological feature important for diagnosis - the degree of keratinization. Squamous cell keratinizing carcinoma is a malignant tumor with morphologically expressed production of polypeptides of the dense fibrous protein keratin and their polymerization, which demonstrates the presence of points of intercellular contact (intercellular bridges) without cytoplasmic continuity. If this feature is absent, the histopathologic description will define squamous cell neorhoving carcinoma.

A highly differentiated squamous cell keratinizing carcinoma is a malignant epithelial neoplasm showing squamous cell differentiation with keratin formation and/or the presence of intercellular bridges. Such tumors show keratinization on histological sections under examination in the form of a large volume of eosinophilic cytoplasm (tissue whose proteins absorb the contrast dye eosin), as well as the presence of keratinized structures (so-called keratin pearls) among the abnormal cells of squamous epithelium.

Symptoms of the squamous cell carcinoma

Localization of squamous cell carcinomas and their symptoms

• Squamous cell carcinoma of the skin

The tumor is also called squamous cell skin cancer; it develops from epithelial keratinocytes, often showing some degree of maturation with keratin formation. It first appears as a skin-colored or light red nodule, usually with a rough surface; it often resembles a wart or skin hematoma with raised edges covered with a scaly crust. [1]

• Squamous cell carcinoma of the ear is a carcinoma of the skin of the ear with a higher rate of metastasis to the lymph nodes and invasion of the cartilage. Its first signs include a scaly area of skin around the ear or tiny white papules on the ear. As the tumor progresses, there may be pain and discharge from the ear, a feeling of stuffiness in the ear with impaired hearing.
• Squamous cell carcinoma of the lung

Squamous cell lung cancer is often called bronchogenic because it develops from cells in the upper layer of the bronchial mucosa. It can be either non-orogenic or orogenic; with time, spread to nearby lymph nodes and various organs is observed.

The most common symptoms are: persistent cough, shortness of breath, wheezing, hoarseness; chest pain, especially when taking deep breaths or coughing; decreased appetite and unexplained weight loss; and feeling tired. [2]

• Bronchial squamous cell carcinoma

Squamous cell bronchial cancer affecting its alveolar epithelium, when scanned, has the appearance of a polyp-like mass that protrudes into the bronchial lumen. The tumor can be manifested by coughing, shortness of breath, weight loss. [3]

• Squamous cell carcinoma of the esophagus

It is the most common histologic type of esophageal cancer. Symptoms manifest as dysphagia (difficulty swallowing), painful swallowing; coughing or hoarseness, heartburn, pressure and chest pain. [4]

• Squamous cell carcinoma of the stomach

Primary squamous cell carcinoma of the stomach is very rare, and the clinical signs in patients are identical to those of other types of gastric cancer, including weight loss, epigastric pain, nausea and vomiting, dysphagia, tarry stools, and blood in the feces. [5]

• Squamous cell carcinoma of the rectum

It is a squamous cell rectal cancer with symptoms such as: diarrhea or constipation, difficulty defecating or more frequent defecation, blood in the stool, lower abdominal pain, unexplained weight loss, weakness or fatigue. [6]

• Squamous cell carcinoma of the anal canal

It is a lesion of the distal colon, information about clinical manifestations of which read in the material - Anorectal cancer.

• Uterine squamous cell carcinoma

How it manifests itself, read:

• Uterine body cancer
• Uterine cancer: symptoms

• Squamous cell carcinoma of the cervix

Such a tumor at an early stage usually does not cause any symptoms. The first signs of later stages are vaginal bleeding after intercourse, between periods or after menopause. Also noted are watery vaginal discharge with a dash of blood (and often with a foul odor, pelvic pain or pain during intercourse. [7] See more. - Cervical Cancer

• Squamous cell carcinoma of the vagina

As it progresses, vaginal squamous cell cancer shows the same symptoms as cervical carcinoma and can also cause frequent and painful urination and constipation. [8]

• Squamous cell carcinoma of the neck and head

As noted by experts, squamous cell cancer of the neck and head affects the outer surfaces of the skin or some tissues in various areas of the head and neck, including the throat, mouth, sinuses, and nose.

• Squamous cell carcinoma of the larynx - Laryngeal Cancer

Squamous cell cancer of the throat (oropharynx) - Throat Cancer

• Squamous cell carcinoma of the nasopharynx

Most patients with this neoplasm have painful enlargement of the upper cervical lymph nodes, and only half of patients have mucous discharge with blood flowing from the nasopharynx into the pharynx along its posterior wall. In addition, there may be obstruction of the eustachian tube with the development of serous otitis media. Headaches cannot be ruled out. [9]

• Nasal squamous cell carcinoma, like other nasal malignancies, is manifested by swelling of the nasal passages and nasal congestion, rhinorrhea (copious liquid discharge) and nasal bleeding, pain and loss of sensation in and around the nose. There may also be ulceration of the mucosa in the nose. Read more - Nasal cancer
• Squamous cell carcinoma of the tonsil - like carcinomas of the base and posterior third of the tongue, soft palate, and posterior and lateral pharyngeal wall - is often defined as oropharyngeal squamous cell carcinoma. If the tumor originates in the tonsil, patients complain of a lumpy feeling in the throat, difficulty swallowing, and pain in the ear and/or neck.
• Oral squamous cell carcinoma has the same symptoms as oral cancer.
• Squamous cell carcinoma of the tongue appears as a red or grayish-white rounded spot, flat or slightly convex, often hard. As the lesion increases in size, pain, difficulty articulating and swallowing may occur.

• Squamous cell carcinoma of the jaw

This tumor develops from odontogenic Malasse epithelial cells, which are remnants of the cells of the periodontal ligament around the tooth (root sheath). Observed symptoms include pain and tooth mobility, impaired chewing and mouth opening, facial swelling, and ulcer formation on the alveolar part of the jaw. [10]

• Squamous cell carcinoma of the penis

Often with such a tumor on the penis there are papillomatous anogenital growths (warts), forming a conglomerate of atypical epithelial cells. Typical symptoms are manifested by itching, swelling, discharge with an unpleasant odor, painful sensations. [11]

Complications and consequences

All complications and consequences that arise in malignant squamous cell carcinomas are associated with tumor metastasis - the formation of additional, often distant pathological foci, the beginning of which are given by circulating tumor cells that penetrate into the lymph or bloodstream.

Diagnostics of the squamous cell carcinoma

Details in the publications:

• Cancer diagnosis
• Cancer screening

Blood tests for oncomarkers p40, p53, CK5 (or CK5/6), Ki-67; for PCNA, p63 and other antigens are mandatory.; human papillomavirus test; swabs and cervical mucosal scrapings for cervical cytology; biopsy and histologic and/or immunohistochemical examination of the tumor tissue sample.

See also - Blood test for cancer cells

Depending on the localization of carcinoma, appropriate instrumental diagnostics is used: in gynecology - pelvic ultrasound, hysteroscopy and colposcopy; in gastroenterology - esophageal and gastric endoscopy, esophagogastroduodenoscopy, esophageal ultrasound, CT and MRI of the intestine, colonoscopy; in pulmonology - radiography, bronchoscopy, endobronchial ultrasound, tomographic scanning of the respiratory organs (computerized and magnetic resonance), etc. д.

Differential diagnosis

Differential diagnosis of squamous cell carcinoma in situ plays a crucial role for the choice of treatment tactics. It is performed by examining histopathological preparations under a microscope and should exclude diseases and pathological conditions in accordance with the localization of squamous cell carcinoma.

For example, in the case of squamous cell carcinoma of the skin, it is basal cell carcinoma, actinic keratosis, keratoacanthoma, blastomycosis, pseudoepitheliomatous hyperplasia; for squamous cell carcinoma of the cervix, it is polyp, cervicovitis, erosion, leiomyoma, cervical lymphoma or sarcoma. And squamous cell carcinoma of the tongue must be distinguished from lymphoma, sarcoma, metastatic tumor, and a variety of benign neoplasms.

Treatment of the squamous cell carcinoma

Comprehensive treatment of squamous cell carcinoma is performed only by specialized medical institutions in accordance with clinical protocols accepted in oncology.

Applies:

• Chemotherapy for various cancers using appropriate chemotherapy drugs, as well as cancer drugs;
• immunotherapy;
• Radiation or radiation therapy for cancer and contact radiation therapy -brachytherapy;
• photodynamic cancer therapy
• surgical treatment - removal of the cancerous tumor, which may be accompanied by lymphadenectomy.

Prevention

While sun protection is needed to prevent squamous cell carcinoma of the skin, and smoking cessation is needed to prevent lung carcinoma, there is a vaccine against HPV, and timely papillomavirus treatment is needed.

In other cases, specific prevention is out of the question. Although a healthy lifestyle and a rational diet are certainly beneficial to the body and its immune system.

Forecast

What is the outcome of squamous cell carcinoma? It all depends on its stage, which in oncology is considered the main prognostic factor for patient survival.

And the higher the stage - from stage 2 (with tumor cells spreading to the nearest lymph nodes) to stage 4 (with distant metastases) - the worse the prognosis. Especially when the tumor is detected at late stages.