Anal Cancer

Anal cancer is a rare cancer that starts in the tissues of the anus, the opening at the end of the large intestine, below the rectum through which stool leaves your body. Affecting approximately 7,000 people in the United States each year, anal cancer can cause rectal bleeding and anal pain.

Anal cancer is divided into cancers of the anal canal and cancers of the lower part of the anus known as the anal margin. The most common type of anal cancer is squamous cell carcinoma which begins in the cells that line the anal margin and most of the anal canal. Cloacogenic carcinomas (also called transitional cell carcinomas) account for the remainder of anal cancers. Other rare anal cancers are: adenocarcinoma of anal ducts, anal Paget’s, anal melanoma, small cell carcinoma, sarcoma (Kaposi’s) and lymphoma.

Surgeons specializing in colon and rectal surgery at Brigham and Women’s Hospital (BWH) are the surgical team for the Gastrointestinal Cancer Treatment Center at Dana-Farber Brigham Cancer Center, a unique center uniting the world’s best gastrointestinal cancer experts. Our board certified surgeons are leaders in advanced laparoscopic and minimally invasive surgical techniques such as sphincter sparing surgery and abdominoperineal resection.

Read frequently asked questions about anal cancer.

Anal Cancer Topics

Risks Factors for Anal Cancer

Factors that contribute to an increased risk for anal cancer include:

  • Human papillomavirus (HPV) infection or genital warts
  • Multiple sex partners
  • Anal intercourse, especially if it is unprotected
  • Weakened immune system
  • History of smoking
  • Older age
  • Repeated inflammation in the anal region

Learn if you are at risk for anal cancer.

Symptoms of Anal Cancer

The most common symptoms of anal cancer are often connected with other less serious medical problems. People experiencing the following symptoms should always see a doctor:

  • Bleeding from the rectum
  • Pain or pressure in the anal area
  • Itching around the anus
  • Discharge from the anus
  • Swollen lymph nodes in the anal or groin area
  • Change in bowel movements
Diagnosis of Anal Cancer

If you are having symptoms of anal cancer, your surgeon will ask you about your health history, your family’s history of cancer and risk factors (above). Additional diagnostic tests include:

  • Digital rectal exam
  • Anoscopy
  • Proctoscopy
  • Endo-anal or endorectal ultrasound
  • Biopsy

The American Cancer Society suggests that people over the age of 50 have a digital rectal exam (DRE) every year.

Learn more about diagnostic tests and procedures for anal cancer.

Stages of Anal Cancer

Staging tests will determine to what degree your anal cancer has spread. Your surgeon may schedule one or more of the following tests to help determine the stage of anal cancer:

  • Transrectal ultrasound
  • Pelvic computed tomography scan (CT scan)
  • Pelvic magnetic resonance imaging (MRI)
  • Chest X-ray or chest computed tomography scan (CT scan)
  • Positron emission tomography scan (PET scan)

Learn more about tests that help evaluate the stage of anal cancer.

With the results of these studies, your doctor will assign your cancer a stage.

The TNM system, developed by the American Joint Committee on Cancer and the International Union Against Cancer, is a standard system used to stage anal cancer. TNM represents:

  • T (tumor) refers to the size of the tumor in the anus and whether or not it has invaded nearby organs.
  • N (node) refers to whether the lymph nodes in the area of the anus have become cancerous.
  • M (metastasis) refers to whether the cancer has spread to other distant organs in the body, such as your bones, liver or lungs.
Treatment for Anal Cancer

Patients have different options when it comes to anal cancer treatment. Often they receive a combination of surgical and medical treatments:

Surgical Treatment

Colon and rectal surgeons at BWH are internationally recognized surgical specialists who are faculty at Harvard Medical School and have years of experience in anal cancer surgery. They have perfected progressive surgical procedures including:

  • Sphincter sparing local resection: If the cancer is small and has not spread, your surgeon may do a local resection. The surgeon removes the tumor along with surrounding tissue. Usually, the sphincter is not damaged. This means you will still be able to pass stool in the normal way.
  • Abdominoperineal resection: Your surgeon removes your anus and your rectum. Without an anus, you will no longer be able to pass stool in the same way. The surgeon makes a permanent opening in your abdomen, called a stoma. A disposable plastic bag is attached to the stoma to collect the stool as it passes through the opening in your abdomen. This is called a colostomy.
  • Local excision for small distal rectal cancers: If cancer is found at an early stage, your surgeon may remove it without cutting through the abdominal wall. Instead, the doctor puts a tube through the rectum into the colon and cuts out the cancer.

Non-Surgical Treatment

What You Should Expect

You will receive a thorough diagnostic examination to evaluate if you have anal cancer and determine what course of treatment is needed. Careful monitoring and the involvement of an experienced colon and rectal surgeon are important to the successful outcome for patients with anal cancer.

If you are having surgery or a procedure, you will likely be scheduled for an in-person or virtual visit to the Weiner Center for Preoperative Evaluation for pre-operative information and tests.

The day of surgery, you will be cared for in the operating room by surgeons, anesthesiologists and nurses who specialize in surgery for patients with anal cancer. After surgery, you will recover in the post-surgical care unit where you will receive comprehensive care by an experienced medical and nursing staff.

Learn more about your hospital stay and returning home.

Multidisciplinary Care

The Gastrointestinal Cancer Treatment Center at Dana-Farber Brigham Cancer Center provides the world’s most advanced and innovative multidisciplinary care for patients with gastrointestinal diseases, such as anal cancer. Our treatment team includes colon and rectal surgeons, medical and radiation oncologists, nutritionists, pathologists, anesthesiologists and gastroenterologists. In addition, patients have full access to BWH’s world-renowned academic medical community with its diverse specialists and state-of-the-art facilities.

Cancer Surgery Appointments and Locations

Contact one of our cancer surgeons in the list at the top of the page to make an appointment.

Brigham and Women’s Hospital, Divisional of General and Gastrointestinal Surgery
75 Francis Street
ASB II – 3rd Floor
Boston, MA 02115

Cancer Surgery Locations


Learn more about anal cancer in our health library.

Visit the Kessler Health Education Library in the Bretholtz Center for Patients and Families to access computers and knowledgeable staff.

Visit the Weiner Center for Preoperative Evaluation

Access a complete directory of patient and family services.

Learn more about Brigham and Women's Hospital

For over a century, a leader in patient care, medical education and research, with expertise in virtually every specialty of medicine and surgery.

About BWH