Anal Cancer

Anal cancer is strongly linked to human papillomavirus (HPV). These viruses are usually harmless in people with healthy immune systems. People with HIV infection are 30 to 50 times more likely to have anal cancer than those without HIV.

HPV is a common virus with more than 100 forms. Some types cause warts. Five types have been linked to cervical cancer in women and anal cancer in both men and women.

Symptoms

The anus is the opening through which solid wastes pass out of the body. It is the opening from the rectum, which is the end of the large intestine. Signs of anal cancer include:

• Bleeding (even a small amount) from the rectum. (Some people with anal cancer mistake this bleeding for hemorrhoids.)
• Pain or pressure around the anus
• Itching or a discharge from anus
• Change in the diameter of the stool
• Change in bowel habits
• A lump near the anus
• Swollen lymph nodes in the anal or groin areas

Causes

In the past, it was thought that anal sex was the main way that HPV spread. However, studies -- of both men and women with HIV infection – show that rates of anal HPV infection are higher in people with HIV no matter how they have sex. 

Risk Factors

Several things may raise the risk of getting anal cancer. These include a history of sexually transmitted diseases and heavy tobacco use. A weakened immune system (having a low CD4 T cell count) raises the chance of getting anal cancer. This suggests that a weakened immune system allows HPV to grow

Prevention

HPV screening is an often-overlooked part of HIV care. Regular screening can help find and treat HPV infection before it becomes a life threatening condition.

Diagnosis

After noting the symptoms and taking a medical history, a doctor will do a physical exam. This will usually include a rectal exam. Wearing thin gloves, the doctor will put a greased finger into the rectum and gently feel for lumps. He or she might order a high-resolution anoscopy. This involves inserting a scope into the anus. The scope makes it possible to magnify the cells to check for abnormalities. A type of acid is also used to detect abnormal cells. Tissue is taken to be examined under a microscope in a lab (a biopsy).

Once the tissue has been analyzed, the cells will be graded as to the type of abnormalities and how widespread they are.

In some cases, a doctor will refer a patient to a proctologist (a specialist in diseases and disorders of the rectum, anus, colon and pelvic floor) or a surgeon.

Treatment

If anal cancer is found, other tests are usually done to see if the cancer has spread. These tests include:

• Chest X-ray to see whether the cancer has spread to the lungs
• Ultrasound, which uses sound waves and their echoes to produce a picture of internal organs or masses
• Computed tomography (CT) scans, which use X-rays to produce many, detailed images as a scanner rotates around the body. A computer then turns the pictures into one image. Sometimes, a dye is used to make parts of the body show up better.
• Magnetic resonance imaging (MRI) scans, which use radio waves and strong magnets to create an image of the body
• Positron emission tomography (PET) scan, which uses a type of sugar that has a radioactive atom. The cancer cells pull in a lot of this sugar. A special camera is used to detect the radioactivity.

The cancer will need to be staged before treatment is planned:

• Stage 0. The cancer is only in the top layer of the anal tissue.
• Stage I. The cancer has spread deeper, but is smaller than an inch.
• Stage II. The cancer has spread beyond the top layer of anal tissue and is larger than an inch. It has not spread to nearby organs or the lymph nodes. (The lymph nodes are small, bean-shaped structures throughout the body. They produce and store infection-fighting cells.)
• Stage III A. The cancer has spread to the lymph nodes around the rectum, bladder or vagina.
• Stage III B. The cancer has spread to the lymph nodes in the middle of the belly or throughout the groin or the cancer has spread to both nearby organs and the lymph nodes around the rectum.
• Stage IV. Cancer has spread to distant lymph nodes within the belly or to organs in other parts of the body.

Usually, the tumor is taken out with surgery. Several types of surgery can be done:

• Removing only the cancer. Often, this saves the ring of muscle (the sphincter) around the anus that opens and closes it to release waste.
• Removing the cancer, the anus and the lower part of the rectum. This surgery requires going in through the belly and the perineum (the space between the anus and the scrotum in men or the vulva in women). The doctor will make an opening to the outside of the body for waste to pass through. This is called a colostomy. The patient will then have to wear a special bag to collect body wastes. The bag sticks to the skin around the opening with special glue. It is thrown away after it is used. The bag doesn’t show under clothing.

Today, radiation or chemotherapy (or both) is done after surgery. This makes treatment effective with less surgery. Radiation therapy uses X-rays or other high-energy rays to kill cancer cells and shrink tumors. One type is beamed through the body to the cancer from the outside. Another is done by putting radioactive materials (radioisotopes) through thin plastic tubes in the area where the cancer was found.

Chemotherapy uses drugs to kill cancer cells. The drugs are either given in pills or through a needle into a vein or muscle. The chemicals enter the blood stream to kill cancer cells throughout the body. Some of these drugs make cancer cells more sensitive to radiation therapy.