Anal Cancer

Anal cancer is cancer that occurs in the perianal region and within the anal canal, the short tube at the end of the rectum where stool leaves the body. Other rare types of cancer may also occur in the anal canal, and these require consultation with your physician or surgeon to determine the appropriate evaluation and treatment. Cells that are becoming malignant or "premalignant" but have not invaded deeper into the skin are often referred to as "high grade anal intraepithelial neoplasia" or HGAIN. While this condition is likely a precursor to anal cancer, it is not anal cancer and is treated differently. Your physician or colon and rectal surgeon can help clarify the differences.

There are nearly 6,000 new cases of anal cancer diagnosed each year in the United States, accounting for about 1 to 2 percent of all intestinal cancers. Unlike some cancers, the incidence of anal cancer is increasing.

Symptoms

Many cases of anal cancer can be found early because they form in a location the physician can see and reach easily. Anal cancers may cause symptoms, such as:

  • Discharge or drainage (mucous, pus or blood) from the anus or rectum
  • A mass or growth in the anal canal
  • Persistent or recurring pain or itching in the anal area
  • Change in bowel habits (having more or fewer bowel movements) or increased straining during a bowel movement
  • Narrowing of the stools
  • Swollen lymph nodes (glands) in the anal or groin areas

Some of these symptoms can also be caused by less serious conditions, such as hemorrhoids. However, if you have any of these symptoms, see your physician or colon and rectal surgeon.

Risk Factors

Anal cancer is commonly associated with an infection by the human papilloma virus (HPV). HPV can also cause warts in and around the anus or genitals in both men and women, but warts do not have to be present for anal cancer to develop. A history of other HPV-related cancers, especially cervical cancer, can put you at increased risk for anal cancer. Additional risk factors for anal cancer include:

  • Age (over age 55)
  • Anal sex
  • Sexually transmitted diseases
  • Multiple sex partners
  • Smoking
  • Weakened immune system (chemotherapy, transplant recipients, patients with HIV)
  • Chronic local inflammation (long-standing anal fistulas or open wounds in the anal area)
  • Pelvic radiation

Prevention

Few cancers can be totally prevented, but the risk of developing anal cancer may be reduced by avoiding risk factors and getting regular checkups. Using condoms may reduce, but not eliminate, the risk of HPV infection. Vaccines against HPV infection have also been shown to reduce the risk of developing anal cancer (in men and women). Those at increased risk for anal cancer should talk to their doctors about anal cancer screening (much like the Pap tests women undergo for cervical cancer screening). Early identification and treatment of premalignant areas in the anus may also prevent the development of anal cancer.

Diagnosis

Anal cancer is usually found on examination of the anus because of the presence of symptoms like those listed above but may be found incidentally on yearly physical exams (rectal exam for prostate check or at the time of a pelvic exam) or on screening tests such as those recommended for preventing or diagnosing colorectal cancer.

Anoscopy, an exam of the anus with a small lighted scope, may be performed to assess any abnormal findings. If an abnormal area in the anus is identified, a biopsy will be performed to determine the diagnosis. If the diagnosis of anal cancer is confirmed, additional tests to determine the extent of the cancer may be recommended.

Treatment

Treatment for most cases of anal cancer is very effective in curing the cancer. Treatment options include:

  • Surgery to remove the cancer
  • Radiation therapy – high-dose X-rays to kill cancer cells
  • Chemotherapy – giving drugs to kill cancer cells
  • Combination therapy with radiation and chemotherapy is now considered the standard treatment for most anal cancers.

Occasionally a very small or early tumor may be removed surgically without the need for further treatment. At times, more major surgery to remove the anal cancer is needed, and this may require the creation of a colostomy where the bowel is brought out to the skin on the belly wall where a bag is then attached to collect the fecal matter. The majority of patients treated for anal cancer will not need a colostomy.