Anal cancer is a disease in which malignant (cancer) cells form in the tissues of the anus. The anus is the end of the large intestine, below the rectum, through which stool (solid waste) leaves the body. Two sphincter muscles open and close the anal opening to let stool pass out of the body. The anal canal, the part of the anus between the rectum and the anal opening, is about 1½ inches long.
Risk factors for anal cancer include the following:
Being over 50 years old.
Being infected with human papillomavirus (HPV).
Having many sexual partners.
Having receptive anal intercourse (anal sex).
Frequent anal redness, swelling, and soreness.
Having anal fistulas (abnormal openings).
These and other symptoms may be caused by anal cancer or by other conditions. A doctor should be consulted if any of the following problems occur:
Bleeding from the anus or rectum.
Pain or pressure in the area around the anus.
Itching or discharge from the anus.
A lump near the anus.
A change in bowel habits.
The following tests and procedures may be used:
Physical exam and history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
Digital rectal examination (DRE): An exam of the anus and rectum. The doctor or nurse inserts a lubricated, gloved finger into the rectum to feel for lumps or anything else that seems unusual.
Anoscopy: An exam of the anus and lower rectum using a short, lighted tube called an anoscope.
Proctoscopy: An exam of the rectum using a short, lighted tube called a proctoscope.
Endo-anal or endorectal ultrasound: A procedure in which an ultrasound transducer (probe) is inserted into the anus or rectum and used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram.
Biopsy: The removal of cells or tissues so they can be viewed under a microscope to check for signs of cancer. If an abnormal area is seen during the anoscopy, a biopsy may be done at that time.
The prognosis (chance of recovery) depends on the following:
The size of the tumor.
Where the tumor is in the anus.
Whether the cancer has spread to the lymph nodes.
The treatment options depend on the following:
The stage of the cancer.
Where the tumor is in the anus.
Whether the patient has human immunodeficiency virus (HIV).
Whether cancer remains after initial treatment or has recurred.
After anal cancer has been diagnosed, tests are done to find out if cancer cells have spread within the anus or to other parts of the body.
The process used to find out if cancer has spread within the anus or to other parts of the body is called staging. The information gathered from the staging process determines the stage of the disease. It is important to know the stage in order to plan treatment. The following tests may be used in the staging process:
CT scan (CAT scan): A procedure that makes a series of detailed pictures of areas inside the body, taken from different angles. For anal cancer, a CT scan of the pelvis and abdomen may be done.
Chest x-ray: An x-ray of the organs and bones inside the chest. An x-ray is a type of energy beam that can go through the body and onto film, making a picture of areas inside the body.
Endo-anal or endorectal ultrasound: A procedure in which an ultrasound transducer (probe) is inserted into the anus or rectum and used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes.
There are different types of treatment for patients with anal cancer.
Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells. There are two types of radiation therapy. External radiation therapy uses a machine outside the body to send radiation toward the cancer. Internal radiation therapy uses a radioactive substance sealed in needles, seeds, wires, or catheters that are placed directly into or near the cancer. The way the radiation therapy is given depends on the type and stage of the cancer being treated.
Chemotherapy is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing the cells or by stopping the cells from dividing. When chemotherapy is taken by mouth or injected into a vein or muscle, the drugs enter the bloodstream and can reach cancer cells throughout the body (systemic chemotherapy). When chemotherapy is placed directly into the spinal column, an organ, or a body cavity such as the abdomen, the drugs mainly affect cancer cells in those areas (regional chemotherapy). The way the chemotherapy is given depends on the type and stage of the cancer being treated.
Local resection: A surgical procedure in which the tumor is cut from the anus along with some of the healthy tissue around it. Local resection may be used if the cancer is small and has not spread. This procedure may save the sphincter 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 resection.
Abdominoperineal resection: A surgical procedure in which the anus, the rectum, and part of the sigmoid colon are removed through an incision made in the abdomen. The doctor sews the end of the intestine to an opening, called a stoma, made in the surface of the abdomen so body waste can be collected in a disposable bag outside of the body. This is called a colostomy. Lymph nodes that contain cancer may also be removed during this operation.