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Anal Cancer

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. The anus is formed partly from the outer, skin layers of the body and partly from the intestine. Two ring-like muscles, called 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.

Anatomy of the lower digestive system, showing the colon and other organs.

The skin around the outside of the anus is called the perianal area. Tumors in this area are skin tumors, not anal cancer.

Being infected with the human papillomavirus (HPV) can affect the risk of developing anal cancer.

Risk factors 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).
• Smoking cigarettes.

Possible signs of anal cancer include bleeding from the anus or rectum or a lump near the anus.

These and other symptoms may be caused by anal cancer. Other conditions may cause the same symptoms. 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.

Tests that examine the rectum and anus are used to detect (find) and diagnose anal cancer.

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 lower part of 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 by a pathologist to check for signs of cancer. If an abnormal area is seen during the anoscopy, a biopsy may be done at that time.

Certain factors affect the prognosis (chance of recovery) and treatment options.

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. The pictures are made by a computer linked to an x-ray machine. A dye may be injected into a vein or swallowed to help the organs or tissues show up more clearly. This procedure is also called computed tomography, computerized tomography, or computerized axial tomography. 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. The echoes form a picture of body tissues called a sonogram.

The following stages are used for anal cancer:

Stage 0 (Carcinoma in Situ)

In stage 0, cancer is found only in the innermost lining of the anus. Stage 0 cancer is also called carcinoma in situ.

Pea, peanut, walnut, and lime show tumor sizes.

Stage I

In stage I, the tumor is 2 centimeters or smaller.

Stage II

In stage II, the tumor is larger than 2 centimeters.

Stage IIIA

In stage IIIA, the tumor may be any size and has spread to either:

• lymph nodes near the rectum; or
• nearby organs, such as the vagina, urethra, and bladder.

Stage IIIB

In stage IIIB, the tumor may be any size and has spread:

• to nearby organs and to lymph nodes near the rectum; or
• to lymph nodes on one side of the pelvis and/or groin, and may have spread to nearby organs; or
• to lymph nodes near the rectum and in the groin, and/or to lymph nodes on both sides of the pelvis and/or groin, and may have spread to nearby organs.

Stage IV

In stage IV, the tumor may be any size and cancer may have spread to lymph nodes or nearby organs and has spread to distant parts of the body.

Recurrent anal cancer is cancer that has recurred (come back) after it has been treated. The cancer may come back in the anus or in other parts of the body.

There are different types of treatment for patients with anal cancer.

Different types of treatments are available for patients with anal cancer. Some treatments are standard (the currently used treatment), and some are being tested in clinical trials. Before starting treatment, patients may want to think about taking part in a clinical trial. A treatment clinical trial is a research study meant to help improve current treatments or obtain information on new treatments for patients with cancer. When clinical trials show that a new treatment is better than the standard treatment, the new treatment may become the standard treatment.

Clinical trials are taking place in many parts of the country. Information about ongoing clinical trials is available from the NCI Web site. Choosing the most appropriate cancer treatment is a decision that ideally involves the patient, family, and health care team.

Three types of standard treatment are used:

Radiation therapy

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

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.

Surgery

• 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.
  
  Anal cancer surgery with colostomy. The anus, rectum, and part of the colon are removed, a stoma is created, and a colostomy bag is attached to the stoma.

Having the human immunodeficiency virus can affect treatment of anal cancer.

Cancer therapy can further damage the already weakened immune systems of patients who have the human immunodeficiency virus (HIV). For this reason, patients who have anal cancer and HIV are usually treated with lower doses of anticancer drugs and radiation than patients who do not have HIV.

Other types of treatment are being tested in clinical trials. These include the following:

Radiosensitizers

Radiosensitizers are drugs that make tumor cells more sensitive to radiation therapy. Combining radiation therapy with radiosensitizers may kill more tumor cells.

This summary section refers to specific treatments under study in clinical trials, but it may not mention every new treatment being studied. Information about ongoing clinical trials is available from the NCI Web site.

Stage 0 Anal Cancer (Carcinoma in Situ)

Treatment of stage 0 anal cancer is usually local resection.

Stage I Anal Cancer

Treatment of stage I anal cancer may include the following:

• Local resection.
• External-beam radiation therapy with or without chemotherapy. If cancer remains after treatment, additional chemotherapy and radiation therapy may be given to avoid the need for a permanent colostomy.
• Internal radiation therapy.
• Abdominoperineal resection, if cancer remains or comes back after treatment with radiation therapy and chemotherapy.
• Internal radiation therapy for cancer that remains after treatment with external-beam radiation therapy.

Patients who have had treatment that saves the sphincter muscles may receive follow-up exams every 3 months for the first 2 years, including rectal exams with endoscopy and biopsy, as needed.

Stage II Anal Cancer

Treatment of stage II anal cancer may include the following:

• Local resection.
• External-beam radiation therapy with chemotherapy. If cancer remains after treatment, additional chemotherapy and radiation therapy may be given to avoid the need for a permanent colostomy.
• Internal radiation therapy.
• Abdominoperineal resection, if cancer remains or comes back after treatment with radiation therapy and chemotherapy.
• A clinical trial of new treatment options.

Patients who have had treatment that saves the sphincter muscles may receive follow-up exams every 3 months for the first 2 years, including rectal exams with endoscopy and biopsy, as needed.

Information about ongoing clinical trials is available from the NCI Web site.

Stage IIIA Anal Cancer

Treatment of stage IIIA anal cancer may include the following:

• External-beam radiation therapy with chemotherapy. If cancer remains after treatment, additional chemotherapy and radiation therapy may be given to avoid the need for a permanent colostomy.
• Internal radiation therapy.
• Abdominoperineal resection, if cancer remains or comes back after treatment with chemotherapy and radiation therapy.
• A clinical trial of new treatment options.

Information about ongoing clinical trials is available from the NCI Web site.

Stage IIIB Anal Cancer

Treatment of stage IIIB anal cancer may include the following:

• External-beam radiation therapy with chemotherapy.
• Local resection or abdominoperineal resection, if cancer remains or comes back after treatment with chemotherapy and radiation therapy. Lymph nodes may also be removed.
• A clinical trial of new treatment options.

Information about ongoing clinical trials is available from the NCI Web site.

Stage IV Anal Cancer

Treatment of stage IV anal cancer may include the following:

• Surgery as palliative therapy to relieve symptoms and improve the quality of life.
• Radiation therapy as palliative therapy.
• Chemotherapy with radiation therapy as palliative therapy.
• A clinical trial of new treatment options.

Information about ongoing clinical trials is available from the NCI Web site.

Treatment of recurrent anal cancer may include the following:

• Radiation therapy and chemotherapy, for recurrence after surgery.
• Surgery, for recurrence after radiation therapy and/or chemotherapy.
• A clinical trial of radiation therapy with chemotherapy and/or radiosensitizers.

This summary section refers to specific treatments under study in clinical trials, but it may not mention every new treatment being studied. Information about ongoing clinical trials is available from the NCI Web site.

The PDQ cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

Changes were made to the descriptions of stages IIIB and IV, and some editorial changes were made.

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PDQ IS A COMPREHENSIVE CANCER DATABASE AVAILABLE ON NCI'S WEB SITE.

PDQ is the National Cancer Institute's (NCI's) comprehensive cancer information database. Most of the information contained in PDQ is available online at NCI's Web site. PDQ is provided as a service of the NCI. The NCI is part of the National Institutes of Health, the federal government's focal point for biomedical research.

PDQ CONTAINS CANCER INFORMATION SUMMARIES.

The PDQ database contains summaries of the latest published information on cancer prevention, detection, genetics, treatment, supportive care, and complementary and alternative medicine. Most summaries are available in two versions. The health professional versions provide detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions provide current and accurate cancer information.

THE PDQ CANCER INFORMATION SUMMARIES ARE DEVELOPED BY CANCER EXPERTS AND REVIEWED REGULARLY.

Editorial Boards made up of experts in oncology and related specialties are responsible for writing and maintaining the cancer information summaries. The summaries are reviewed regularly and changes are made as new information becomes available. The date on each summary ("Date Last Modified") indicates the time of the most recent change.

PDQ ALSO CONTAINS INFORMATION ON CLINICAL TRIALS.

Before starting treatment, patients may want to think about taking part in a clinical trial. A clinical trial is a study to answer a scientific question, such as whether one treatment is better than another. Trials are based on past studies and what has been learned in the laboratory. Each trial answers certain scientific questions in order to find new and better ways to help cancer patients. During treatment clinical trials, information is collected about new treatments, the risks involved, and how well they do or do not work. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard."

Listings of clinical trials are included in PDQ and are available online at NCI's Web site. Descriptions of the trials are available in health professional and patient versions. Many cancer doctors who take part in clinical trials are also listed in PDQ. For more information, call the Cancer Information Service 1-800-4-CANCER (1-800-422-6237); TTY at 1-800-332-8615.

Date Last Modified: 2005-04-14

If you want to know more about cancer and how it is treated, or if you wish to know about clinical trials for your type of cancer, you can call the NCI's Cancer Information Service at 1-800-422-6237, toll free. A trained information specialist can talk with you and answer your questions.