The anus is the opening of the rectum where waste material passes out of the body. In anal cancer, malignant cells (cancerous cells) are found in the anus.
Symptoms of anal cancer include bleeding, pain, discomfort, itching, discharge from the anus, or a lump near the anus. Sometimes people confuse the general symptoms of anal cancer with symptoms from hemorrhoids, and the correct diagnosis is often delayed.
Causes and Risk Factors
Less than 1.5% of cancers in the intestines are anal cancer. However, some common conditions increase the risk of developing anal cancer:
- Human Papilloma Virus (HPV) - A common STD (sexually transmitted infection), HPV can cause anal warts, small raised growths around the anus or genitals. Exposure to HPV increases the risk of developing anal cancer.
- Weakened immune system - Individuals with human immunodeficiency virus (HIV) or those who take immunosuppressant medications (such as kidney transplant recipients) are more likely to develop anal cancer.
Any patient with symptoms related to the anus or rectum should have a thorough physical exam with special attention to the anal and rectal region.
The diagnosis of anal cancer is made by performing a biopsy of the abnormal area, in the operating room. A small biopsy can be performed in the office with a local anesthetic.
Stages of anal cancer are classified as follows:
- Stage 0 - Very early cancer. The cancer cells are confined to the top layer of anal tissue.
- Stage 1 - A tumor less than 2 centimeters (1 inch) in size. No evidence of spread to the lymph nodes.
- Stage 2 - A tumor greater than 2 centimeters (1 inch) in size. No invasion to adjacent organs such as the vagina, urethra or bladder. No evidence of spread to the lymph nodes.
- Stage 3a - A large tumor that invades into adjacent organs. No evidence of spread to the lymph nodes; or the tumor has spread only to the lymph nodes around the rectum.
- Stage 3b - A large tumor that invades into adjacent organs and has spread to the lymph nodes; or any size tumor with extensive spread to the lymph nodes, but no evidence of spread to distant organs.
- Stage 4 - Any size tumor that has spread to the lymph nodes and distant organs.
After the diagnosis is made, there are two treatment options. For very early cancers, where the tumor does not invade deep into the anal tissue, the tumor is removed with surgery only. For most cancers, however, the first treatment is intravenous chemotherapy and radiation to the pelvis. About 90% of tumors are cured with chemo-radiation. Approximately 85% have no recurrence of the tumor five years after treatment, but frequent physical examinations and diagnostics tests are necessary to be certain the tumor does not recur.