Anal Cancer, which is rare in the general population, is somewhat common among men who have sex with men. It is also increased in women who have anal sex with multiple partners. It is something you should know about. It is very difficult to treat, and like most cancers, survival is much better if it is detected early. Some new important studies about it have been published recently. It is being talked about more, and recommendations for screening will probably appear over the next few years.
Anal cancer bears some resemblance to cervical cancer in women. Like cervical cancer, anal cancer is often caused by infection with the human papillomavirus (HPV), the virus that causes genital warts. It is spread by sexual contact. While unprotected anal intercourse is the most common way to get the infection (and warts) in and around the anus, anal penetration is not necessary. Rubbing the penis outside the anus can pass the virus. It may also be spread by hands or by sex toys. The infection causes small warts around and inside the anus or in the genital area. However, noticeable warts do not have to be present for a significant infection or cancer to exist.
Most people with anal warts do not develop anal cancer. People with HIV, especially with low CD4 counts, are much more likely to develop cancer from anal warts. A normal immune system is often able to kill the cancer cells. However, anal cancer does occur in HIV negative men. Certain strains of the HPV virus are more likely to cause cancer. Ironically, some of the most cancer producing strains make flat warts that are difficult to see.
There are several methods to test for HPV infection, pre-cancerous cells, and cancer in the anal area. The most accurate is biopsy, done by snipping a small piece of tissue from the anal canal. Because it is costly and a little painful, it is usually reserved for patients with a suspected problem or a positive Pap smear. A Pap smear usually refers to a sample taken from a womans cervix, but it may be done from other areas of the body. For an anal Pap smear, a cotton swab is placed in the anus and rotated to pick up cells. It is painless. The sample is then looked at under a microscope to identify abnormal cells. There are also other tests that use a swab and high tech methods to identify the virus.
Routine screening for anal cancer with anal Pap smears in high-risk groups is not done yet, but it may be soon. In the last 4 years, there have been numerous articles in the medical literature about screening for anal cancer and HPV infections. They mostly recommend it for homosexual and bisexual men who are HIV positive, the group at highest risk. In May, there was an article in the prestigious Journal of the American Medical Association (JAMA) showing the usefulness of routine anal Pap smear screening of HIV positive gay men. It demonstrated a decrease in death and illness at a cost similar to screening tests now in use for other illnesses. However, there are still questions that need to be answered and logistical problems to be solved, before screening programs are widely accepted.
What can you do before testing is available? Pay close attention to your body. If you have anal or genital warts, keep a close eye on them. Find a doctor you feel comfortable with, and have them checked, both for treatment to remove them and to look for suspicious areas. If you have any rectal problems, see your doctor. Most importantly, make sure you are always having safer sex. Its not just for HIV prevention. There are many illnesses that are passed sexually, and others will be discovered. Protect yourself.
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