Treatment for Anal Cancer
Treatment of anal cancer depends on the type of tumor and its stage of development. There are three types of treatment:
- Surgical resection; may be done with laser surgery (usually Stages 0–II)
- Radiation (usually Stage II and higher)
- Chemotherapy (usually Stage II and higher)
Surgery to Treat Anal Cancer
A local surgical resection (removal) of the tumor and a small amount of surrounding tissue may suffice in cases of Stage 0 cancer, where the cancer has not metastasized and does not affect the sphincters.
In later stages, where cancer has spread, a surgeon may perform an abdominoperineal resection to remove affected tissue, lymph nodes, or sections of or organs in the abdomen. This procedure requires a colostomy, wherein the anus is removed and waste is diverted from the colon through a surgically created opening, through the abdominal wall, and to an external bag for disposal. Abdominoperineal resection is used less frequently because radiation and chemotherapy are effective and do not require a colostomy.
Resection can cause anal stenosis (narrowing) of the anal canal and anus due to scar tissue. Surgery is sometimes required to widen the anus and restore proper function.
Radiation Therapy to Treat Anal Cancer
Radiation, the shrinkage of cancerous tumors with energy waves (e.g., x-rays), is performed with external radiation or internal radioactive implants (radioisotopes). Internal radiation using implants (brachytherapy) involves placing plastic-covered radioactive seeds (pellets) inside the anus, near the cancerous tissue, to shrink tissue. The seeds stay in for the appropriate length of time, perhaps permanently, and require fewer trips to the physician's office. Radiation may be combined with chemotherapy. Radiation causes side effects including loss of control of the sphincter muscle (incontinence), temporary browning of the skin, and fatigue.
Chemotherapy to Treat Anal Cancer
Chemotherapy involves drug treatment to kill cancer cells. Drugs used to treat anal cancer include 5-fluorouracil (5-FU), mitomycin, and cisplatin, which are administered orally or intravenously. Chemotherapy is a systemic treatment; the drugs enter and travel throughout the body to kill cancer cells wherever they are. All of these drugs (antineoplastic agents) inhibit the normal production and use of deoxyribonucleic acid (DNA), which is needed for cell growth and division. Arrested cell growth results in tumor shrinkage.
Chemotherapy drugs cause acute side effects, including nausea, fatigue, vomiting, fever, diarrhea, and sensitivity to sunlight. Certain drugs are associated with specific side effects. 5-fluorouracil may cause low white blood cell count, ulcers, and visual problems. Mitomycin is associated with bone marrow, kidney, mucous membrane, and pulmonary toxicity, as well as kidney failure. Cisplatin may cause hearing problems, serious disorientation, and anaphylactic (allergic shock) reactions, including respiratory distress and swelling.
Anal Cancer Prevention
Avoiding contracting HPV and anogenital warts is the best prevention for anal cancer. Using latex condoms during anal sex significantly reduces the risk for HPV and other STDs, but condoms may not prevent HPV infection.
If benign anal lesions are found, routine anal Pap smears and biopsies may detect cancerous cells early enough for successful treatment. Biopsy is recommended every 6 to 12 months for less serious lesions and 3 to 4 months for more serious ones. It is important to consult a physician when a lesion is found anywhere in the anal region.
In December 2010, the U.S. Food and Drug Administration (FDA) approved the Gardasil vaccine to reduce the risk for precancerous anal lesions and anal cancer associated with some types of HPV (e.g., types 6, 11, 16, 18). The vaccine, which also is approved to help prevent cervical cancer and other cancers of the female reproductive tract and genital warts, can reduce anal cancer risk in males and females between the ages of 9 and 26.