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Types of Anal Cancer
Squamous cell carcinomas are the most common type of anal cancer. These tumors begin in the cells that line the lower part of the anus and most of the anal canal. In its earliest stages it is known as carcinoma in situ or CIS. It may also be called Bowen disease. In CIS, the cancer is only in the surface cells and has not spread to any other tissue. If the cancer has spread beyond the surface cells it is called invasive.
Cloacogenic carcinomas: This is a type of squamous cell cancer that starts in an area of the anus called the cloaca.
Adenocarcinomas: A small number of anal cancers start in the glands found in the anal area. These cancers are known as adenocarcinomas. Paget disease is a type of adenocarcinoma that spreads through the surface layer of skin and can occur in the anal area. This should not be confused with Paget disease of the bone, which is a very different disease.
Skin Cancers: A small percentage of anal cancers are basal cell carcinomas, a type of skin cancer. Another 1%-2% are melanomas, another type of skin cancer. Melanomas are far more common on parts of the body that are exposed to the sun. Unfortunately, most anal melanomas are found at a late stage because they are hard to see.
Facts about Anal Cancer- Anal cancer is fairly rare.
- The American Cancer Society estimates that in 2006 there will be 4,660 new cases of anal cancer in the United States. About 660 people will die of the disease this year.
- Women get anal cancer more often than men.
- Anal cancer is found mainly in adults older than age 35.
- While anal cancer is a serious disease, treatment is very effective. Most people with this cancer will be cured.
General Risk Factors
HPV (human papillomavirus): Most doctors think that squamous cell anal cancer is caused by a type of this virus called HPV-16. The virus spreads during sex. It is more likely to be found in people who have many sex partners. One sign of infection with this virus is genital warts.
Sex: Having many sex partners is a risk factor for women. Having anal sex is a risk factor for both men and women, especially under the age of 30.
Smoking: Harmful chemicals from smoke get into the bloodstream and increase the risk of anal cancer in smokers. People who smoke are about 4 times more likely to have cancer of the anus compared with people who never smoked. Quitting smoking reduces this risk.
Other medical problems: Long-term problems in the anal area such as abnormal openings (fistulas) can increase the chances of getting anal cancer. People with weakened immune systems are at higher risk for anal cancer. This includes people who have had transplants (who must take drugs to suppress their immune systems) and people with HIV infection (human immunodeficiency virus or the virus that causes AIDS.
How is Anal Cancer Found?
The American Cancer Society suggests that all men over the age of 50 be offered a rectal exam every year to check for prostate cancer. For women, the rectal exam is done as part of the pelvic exam. If you are concerned about anal cancer, ask your doctor if you should have the exam more often - or other tests as well.
Recently, doctors have tested people at high risk for sexually transmitted diseases. The test is much like the Pap smear for cervical cancer. Some doctors think that this test should be done routinely for people at high risk for anal cancer. That would include:- HIV-positive men who have sex with men and
- HIV-positive women who have anal sex
- Testing all positive HIV-positive people may also be helpful. People with positive results should be referred for a biopsy and, depending on the results, treated.
People who have symptoms of anal cancer may notice one or more of the following:- bleeding or itching around the anus
- pain in the anal area
- change in the width of the stool, stool may be narrower than usual
- swollen lymph nodes in the anal or groin area
- abnormal discharge from the anus
These symptoms can also be caused by something other than cancer, but only your doctor can tell for sure. Talk to your doctor right away if you notice any of these problems.
If your doctor has any reason to suspect anal cancer, you will need to have some more tests. Most of these tests allow the doctor to look inside the anus. Your doctor can explain the details of any other tests to be done.
Diagnostic Testing
If you have cancer, other tests such as the ones below can help to find the extent of the cancer and whether it has spread.
CT Scan (computed tomography, also called a CAT scan): This scan uses x-rays to take many pictures of the body that are then combined by a computer to give a detailed cross-sectional picture. CT scans take longer than regular x-rays and you need to lie still on a table for 15 to 30 minutes. You might also feel a bit confined by the machine you lie in while the pictures are taken. But CT scans are getting faster all the time. A CT scan can help tell whether anal cancer has spread to the liver or other organs.
Learn about Marin Cancer Institute’s state-of-the-art equipment, which is used to diagnose and treat cancer.
Treatment
Most patients with anal caner will be cured. The treatment is usually a combination of chemotherapy and radiation therapy given simultaneously. Although the treatment is generally successful, there can be serious side effects, (short term and long term). It is important to discuss any concerns or symptoms with your physician.
Chemotherapy
There are a few different chemotherapy medications that can be used to treat anal cancer. The selection of a particular type of chemotherapy is generally based upon the stage of the cancer and he overall physical condition of patient. Chemotherapy is given with radiation therapy with the goal of eradicating the anal cancer.
Radiation Therapy
Radiation therapy may be directed to the anal area alone or it may be directed to the anal area and to lymph nodes in the pelvis. When radiation therapy is given together with chemotherapy there is a very high probability that anal cancer will be eradicated and that surgery can be avoided. The combination of radiation and chemotherapy is a very effective treatment, but this treatment is also associated with a number of short term and long-term side effects. Your physician can make recommendations to help alleviate adverse symptoms related to side effects of your treatment. Make sure to discuss any concerns or symptoms with your physician in a timely manner.
Surgery
A surgical biopsy is required to confirm the diagnosis of anal cancer. Surgery is not commonly used to treat anal cancer since surgical removal of the cancer often requires removal of the entire anal sphincter and the formation of a colostomy.
Your Care Team
Meet the team of surgeons, radiation oncologists, medical oncologists and more, who make up the Gastrointestinal Cancer Program at the Marin Cancer Institute, and dedicate their lives to their patients’ well being.
*Statistics provided by the American Cancer Society. Revised 2006.
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