Anal Cancer

What is anal cancer?

Anal cancer is a disease in which malignant (cancerous) cells form in the tissues of the anus. The anus is the end of the large intestine, through which stool is expelled from the body. The anus is partly formed by the outer layers of skin and partly by the intestine. Two ring-shaped muscles, called sphincter muscles, open and close the anal opening to facilitate bowel movements. The anal canal, the section of the anus between the rectum and the anal opening, is about 4 cm long.

The skin surrounding the outside of the anus is called the perianal area. Tumors in this area are skin tumors and are not classified as anal cancer. Individuals infected with the human papillomavirus (HPV) may have a higher risk of developing anal cancer.

Όσα άτομα έχουν μολυνθεί με ιό των ανθρωπίνων θηλωμάτων (HPV) μπορεί να έχουν μεγαλύτερο κίνδυνο ανάπτυξης καρκίνου του πρωκτού.

Risk factors include:

• Age over 50
• History of infection with the human papillomavirus (HPV)
• Individuals with multiple sexual partners
• Individuals susceptible to anal intercourse
• Frequent anal irritation, swelling, and pain
• Anal fistulas
• Smoking

Possible symptoms of anal cancer include bleeding from the anus or rectum, or lesions near the anus. These and other symptoms can be caused by anal cancer, but other conditions can also cause the same symptoms. You should consult your doctor if you experience any of the following issues:

• Bleeding from the anus or rectum
• Pain or pressure in the anal area
• Itching around the anus
• A lesion near the anus (abrasions, ulcers, lumps, etc.)
• Changes in bowel habits

Exams of the rectum and anus used to detect and diagnose anal cancer

Physical examination and history: A general health check-up to assess symptoms of disease, including examining for any unusual lesions or other anomalies. A history of the patient’s habits, health, past illnesses, and treatments will also be taken.

Digital rectal examination: An examination of the anus and rectum. The doctor inserts a gloved, lubricated finger into the anus and the last part of the rectum to feel for lesions or anything else that appears abnormal.

Anoscopy: An examination of the anus and the last part of the rectum using a tube that emits light, called an anoscope.

Endoanal or endorectal ultrasound: A procedure in which a special ultrasound endoscope is inserted into the anus or rectum to produce high-frequency sound waves (ultrasound) for detailed imaging of the inner lining and walls, as well as nearby organs.

Biopsy: The removal of cells or tissues so they can be examined under a microscope by a pathologist to check for signs of cancer. If an abnormal area is observed during anoscopy, a biopsy may be taken at that time.

Ορισμένοι παράγοντες που επηρεάζουν την πρόγνωση και τις επιλογές θεραπείας.

Factors affecting prognosis and treatment options What does prognosis depend on?

• The size of the tumor
• Whether the tumor is in the anal area
• Whether the cancer has spread to the lymph nodes

Treatment options depend on:

• The stage of cancer
• Whether the tumor is in the anal area
• Whether the patient has the human immunodeficiency virus (HIV)
• Whether the cancer remains after initial treatment or has recurred

What are the stages of anal cancer?

Once anal cancer is diagnosed, further tests are conducted to determine whether cancerous cells have spread within the anus or to other parts of the body. The process used to determine whether cancer has spread is called staging. The information gathered from staging determines the stage of the disease. Knowing the stage is important for planning treatment.

The following tests may be used in the staging process:

CT scan: An exam that produces a series of detailed images of areas inside the body taken from different angles. The images are made by a computer connected to an X-ray machine. A contrast dye may be injected into a vein or taken by mouth to help organs or tissues appear clearer. This test is also known as computed tomography (CT). For anal cancer, a CT scan of the pelvis and abdomen may be performed.

Chest X-ray: An X-ray of the organs and bones in the chest. An X-ray is a form of energy that passes through the body and onto film, creating an image of areas inside the body.

MRI (magnetic resonance imaging): An exam that uses a magnet, radio waves, and a computer to create a series of detailed images of areas inside the body. This procedure is also known as nuclear magnetic resonance imaging (NMRI).

PET scan (positron emission tomography): An exam that looks for malignant cells throughout the body. A small amount of radioactive glucose (sugar) is injected into a vein. The PET scanner rotates around the body and creates an image of where glucose is being used in the body. Cancer cells in a tumor appear brighter in the image because they are more active and take up more glucose than normal cells.

How does cancer spread in the body?

Cancer can spread in three ways:

• Through tissue: Cancer invades nearby normal tissue.
• Through the lymphatic system: Cancer invades the lymphatic system and travels through the lymphatic vessels to other parts of the body.
• Through the blood: Cancer invades the veins and capillaries and travels through the blood to other parts of the body.

When cancer cells migrate from the primary (original) tumor and travel through the lymph or blood to other parts of the body, a new (secondary) tumor may form. This process is called metastasis. The secondary (metastatic) tumor is the same type of cancer as the primary tumor.

For example, if breast cancer spreads to the bones, the cancer cells in the bones are breast cancer cells. The disease is metastatic breast cancer, not bone cancer.

What are the appropriate treatments for anal cancer?

Three main types of treatment are used:

Radiation therapy

This treatment uses high-energy X-rays or other forms of radiation to destroy cancer cells. There are two types of radiation therapy. External beam radiation therapy uses a machine outside the body to direct radiation at the cancer. Internal radiation therapy uses a radioactive substance placed directly in or near the cancer. The type of radiation therapy given depends on the type and stage of cancer.

Chemotherapy

This cancer treatment uses drugs to stop the growth of cancer cells, either by killing them or stopping their division. When chemotherapy is taken orally or by intravenous injection, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly in the spinal column, an organ, or a body cavity like the abdomen, the drugs primarily affect cancer cells in those areas (regional chemotherapy). The type of chemotherapy depends on the type and stage of cancer.

Surgical treatment

• Local excision: A surgical procedure in which the tumor is cut out from the anus along with surrounding healthy tissue. Local excision may be performed if the cancer is small and has not spread. This procedure can preserve the anal muscles so the patient can still control bowel movements. Tumors that develop in the lower part of the anus can often be removed with local excision.
• Abdominoperineal resection: A surgical procedure in which the anus, rectum, and part of the sigmoid colon are removed through an incision made in the abdomen. The doctor stitches the end of the intestine to an opening, called a stoma, made on the surface of the abdomen so that waste can be collected in a disposable bag outside the body. This is called a colostomy. Lymph nodes containing cancer may also be removed during this surgery.

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