
Anal cancer is an uncommon type of cancer that occurs in the anal canal. The anal canal is a short tube at the end of your rectum through which stool leaves your body. Anal cancer is very different from colorectal cancer, which is much more common. Anal cancer, though rare, is a lump created by the abnormal and uncontrolled growth of cells in the anus. Most anal cancers (80%) are diagnosed in people who are over age 60. Prior to age 35, anal cancer is more common in men. However, after age 50, anal cancer is slightly more common in women.
The incidence rate of anal cancer is six times higher in single men as compared to married men. Receptive anal intercourse is strongly related to the development of anal cancer. Anal infection with human papillomavirus (HPV) resulting in genital warts is a major risk factor for the cancer.
Immunocompromised patients, such as those with HIV disease, are prone to get anal cancer. In this subgroup, the prognosis is worse, than for non-immunocompromised patients.
The most common symptom associated with anal cancer is bleeding. Itching at the anal opening may also be a symptom, although many people, initially, attribute such bleeding and itching to haemorrhoids. This can delay the diagnosis of anal cancer. Other signs and symptoms of anal cancer may include:
Anal cancer occurs when a genetic mutation turns normal, healthy cells in the anal canal into abnormal cells. Healthy cells grow and multiply at a set rate, eventually dying at a set time. Abnormal cells continue to grow and multiply and do not die. The accumulating abnormal cells form a mass (tumour). Cancer cells invade nearby tissues and can separate from an initial tumour to spread elsewhere in the body (metastasize).
Anal cancer is closely related to a sexually transmitted infection called human papillomavirus (HPV). Evidence of HPV is detected in the majority of anal cancers. HPV is thought to be the most common cause of anal cancers.
Several factors have been found to increase the risk of anal cancer, including:
Tests and procedures used to diagnose anal cancer include:
Once it's confirmed that you have anal cancer, the doctor may recommend additional tests to determine whether your cancer has spread to your lymph nodes or to other areas of your body. This is called staging.
Tests may include:
The information from these procedures is used to assign the cancer a stage. The stages of anal cancer are indicated using Roman numerals ranging from 0 to IV, with the lowest stages indicating that the cancer is small and confined to the anus. By stage IV, the cancer has spread to distant areas of the body.
There are different ways to treat anal cancer, depending upon which stage it is in, if the patient has HIV or if the cancer is a recurrence. Doctors usually treat anal cancer with a combination of chemotherapy and radiation. Combined, these two treatments enhance each other and improve chances for a cure.
Radiation Therapy: It 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 led directly into or near the cancer. The way radiation therapy is given depends on the type and stage of cancer.
Chemotherapy: This is a cancer treatment that uses drugs to stop the growth of cancer cells, either by killing them or by stopping them from dividing. When chemotherapy is taken orally 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 mode of administration of chemotherapy depends on the type and the stage of the cancer being treated.
Surgery: Doctors typically use different procedures to remove anal cancer based on the stage of the cancer: