This information is produced and provided by the National Cancer Institute (NCI). The information in this topic may have changed since it was written. For the most current information, contact the National Cancer Institute via the Internet web site at http://cancer.gov or call 1-800-4-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 and let stool pass out of the body. The anal canal, the part of the anus between the rectum and the anal opening, is about 1-1½ 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) increases the risk of developing anal cancer.
Risk factors include the following:
Signs of anal cancer include bleeding from the anus or rectum or a lump near the anus.
These and other signs and symptoms may be caused by anal cancer or by other conditions. Check with your doctor if you have any of the following:
Tests that examine the rectum and anus are used to detect (find) and diagnose anal cancer.
The following tests and procedures may be used:
Certain factors affect the prognosis (chance of recovery) and treatment options.
The prognosis (chance of recovery) depends on the following:
The treatment options depend on the following:
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:
There are three ways that cancer spreads in the body.
Cancer can spread through tissue, the lymph system, and the blood:
Cancer may spread from where it began to other parts of the body.
When cancer spreads to another part of the body, it is called metastasis. Cancer cells break away from where they began (the primary tumor) and travel through the lymph system or blood.
The metastatic tumor is the same type of cancer as the primary tumor. For example, if anal cancer spreads to the lung, the cancer cells in the lung are actually anal cancer cells. The disease is metastatic anal cancer, not lung cancer.
The following stages are used for anal cancer:
Stage 0 (Carcinoma in Situ)
In stage 0, abnormal cells are found in the innermost lining of the anus. These abnormal cells may become cancer and spread into nearby normal tissue. Stage 0 is also called carcinoma in situ.
Tumor sizes. The size of a tumor may be compared to the size of a pea (1 cm), peanut (2 cm), grape (3 cm), walnut (4 cm), lime (5 cm), egg (6 cm), peach (7 cm), or grapefruit (10 cm).
In stage I, cancer has formed and the tumor is 2 centimeters or smaller.
In stage II, the tumor is larger than 2 centimeters.
In stage IIIA, the tumor may be any size and has spread to either:
In stage IIIB, the tumor may be any size and has spread:
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. 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. Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Three types of standard treatment are used:
Radiation therapy is a cancer treatment that uses high-energy x-rays or other types of radiation to kill cancer cells or keep them from growing. There are two types of radiation therapy:
The way the radiation therapy is given depends on the type and stage of the cancer being treated. External and internal radiation therapy are used to treat anal cancer.
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 cerebrospinal fluid, 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.
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.
New types of treatment are being tested in clinical trials.
This summary section describes treatments that are being studied in clinical trials. It may not mention every new treatment being studied. Information about clinical trials is available from the NCI website.
Radiosensitizers are drugs that make tumor cells more sensitive to radiation therapy. Combining radiation therapy with radiosensitizers may kill more tumor cells.
Treatment for anal cancer may cause side effects.
For information about side effects caused by treatment for cancer, see our Side Effects page.
Patients may want to think about taking part in a clinical trial.
For some patients, taking part in a clinical trial may be the best treatment choice. Clinical trials are part of the cancer research process. Clinical trials are done to find out if new cancer treatments are safe and effective or better than the standard treatment.
Many of today's standard treatments for cancer are based on earlier clinical trials. Patients who take part in a clinical trial may receive the standard treatment or be among the first to receive a new treatment.
Patients who take part in clinical trials also help improve the way cancer will be treated in the future. Even when clinical trials do not lead to effective new treatments, they often answer important questions and help move research forward.
Patients can enter clinical trials before, during, or after starting their cancer treatment.
Some clinical trials only include patients who have not yet received treatment. Other trials test treatments for patients whose cancer has not gotten better. There are also clinical trials that test new ways to stop cancer from recurring (coming back) or reduce the side effects of cancer treatment.
Clinical trials are taking place in many parts of the country. See the Treatment Options section that follows for links to current treatment clinical trials. These have been retrieved from NCI's listing of clinical trials.
Follow-up tests may be needed.
Some of the tests that were done to diagnose the cancer or to find out the stage of the cancer may be repeated. Some tests will be repeated in order to see how well the treatment is working. Decisions about whether to continue, change, or stop treatment may be based on the results of these tests.
Some of the tests will continue to be done from time to time after treatment has ended. The results of these tests can show if your condition has changed or if the cancer has recurred (come back). These tests are sometimes called follow-up tests or check-ups.
For information about the treatments listed below, see the Treatment Option Overview section.
Stage 0 (Carcinoma in Situ)
Treatment of stage 0 is usually local resection.
Use our clinical trial search to find NCI-supported cancer clinical trials that are accepting patients. You can search for trials based on the type of cancer, the age of the patient, and where the trials are being done. General information about clinical trials is also available.
Stage I Anal Cancer
Treatment of stage I anal cancer may include the following:
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:
Stage IIIA Anal Cancer
Treatment of stage IIIA anal cancer may include the following:
Stage IIIB Anal Cancer
Treatment of stage IIIB anal cancer may include the following:
Stage IV Anal Cancer
Treatment of stage IV anal cancer may include the following:
Treatment of recurrent anal cancer may include the following:
For more information from the National Cancer Institute about anal cancer, see the following:
For general cancer information and other resources from the National Cancer Institute, see the following:
Physician Data Query (PDQ) is the National Cancer Institute's (NCI's) comprehensive cancer information database. 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 come in two versions. The health professional versions have detailed information written in technical language. The patient versions are written in easy-to-understand, nontechnical language. Both versions have cancer information that is accurate and up to date and most versions are also available in Spanish.
PDQ is a service of the NCI. The NCI is part of the National Institutes of Health (NIH). NIH is the federal government's center of biomedical research. The PDQ summaries are based on an independent review of the medical literature. They are not policy statements of the NCI or the NIH.
Purpose of This Summary
This PDQ cancer information summary has current information about the treatment of anal cancer. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care.
Reviewers and Updates
Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Date Last Modified") is the date of the most recent change.
The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Adult Treatment Editorial Board.
Clinical Trial Information
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 the effects of a new treatment and how well it works. If a clinical trial shows that a new treatment is better than one currently being used, the new treatment may become "standard." Patients may want to think about taking part in a clinical trial. Some clinical trials are open only to patients who have not started treatment.
Clinical trials are listed in PDQ and can be found online at NCI's website. 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).
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The best way to cite this PDQ summary is:
PDQ® Adult Treatment Editorial Board. PDQ Anal Cancer Treatment. Bethesda, MD: National Cancer Institute. Updated <MM/DD/YYYY>. Available at: https://www.cancer.gov/types/anal/patient/anal-treatment-pdq. Accessed <MM/DD/YYYY>. [PMID: 26389368]
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Last Revised: 2017-12-07
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