Types of HPV That Are Associated with Cancer
What is HPV?
The human papilloma virus (HPV) is the virus responsible for warts. There are more than one-hundred different types of HPV. About forty of these are mucosal strains, meaning that they infect the mucosal tissue such as the vulva, vagina, penis, anus, urethra, mouth, and throat. Because they primarily affect the genital tissues, they are often called genital or venereal strains. Several different genital cancers, primarily of the cervix but also of the penis, anus, and vagina, have been linked to specific strains of HPV. In fact, at least ninety-nine percent, if not all, cases of cervical cancer can be traced to HPV infections. In rare cases, people who have contracted HPV infections in the mouth and throat as a result of performing oral sex have develop cancer of the tongue, tonsils, or throat. There is also some evidence that people with very poor immune response who develop common warts as a result of non-mucosal HPV infections of the skin may be at increased risk of skin cancer, but the connection is rather tenuous as of now.
What Types of HPV Can Cause Cancer?
Specific strains of HPV have been identified as being "high risk" meaning that they lead to cancer in a certain percent of patients who contract them. Two strains in particular, 16 and 18, have been shown to account for roughly seventy percent of cervical cancer cases. Other related strains can also cause cancer, although this is rarer. These are not, usually, the strains that cause warts. Rather, infection is generally asymptomatic, and most people recover from them without ever knowing they had them. In some cases, however, infections are revealed when they begin to cause pre-cancerous or cancerous changes.
How Can HPV Cause Cancer?
When the body doesn't fight off an infection of certain strains of HPV, the virus can stay in the cells for a long time. If it is active for more than a couple of years, it can begin to cause changes in the cells. These cell changes can, in some cases, develop into cancer.
The only sure way not to contract HPV is not to engage in sexual activity. Limiting your number of sexual partners and knowing their sexual history can also be helpful, although HPV is so common that most people who have sex will get an infection eventually. Always using condoms may lower your risk slightly, but unfortunately, the virus often infects areas not protected by the condom. Fortunately, though, most cases of HPV infections can't, or never do, lead to cancer. But the risk exists, so it is vital that you take responsibility for your health. The most important thing to do to protect you, as a woman, from developing cancer is to have regular pap smears. Since the types of HPV that cause cancer doesn't have any symptoms, this is the only way to know if you'se been exposed and your cells are changing as a result. During a pap smear, a physician collects a sample of cells from the cervix. These cells are then analyzed for abnormalities. This means that pre-cancerous cells can be caught and removed early, before they become cancerous. Some physicians are now doing anal pap smears on men and women who engage in anal sex, since the number of cases of cancer of the anus has been increasing. For women, there is now a vaccine available for strains 16 and 18, the two most commonly linked to cervical cancer (as an added benefit, it also protects you from strains 6 and 11, the strains that cause most cases of genital warts). If you're already been exposed to these strains, however, the vaccine won't help. For this reason, it's recommended that women take the vaccine before becoming sexually active. However, even women who have been sexually active haven't been exposed to all four strains, so the vaccine can still be beneficial. Studies are being conducted in men right now to see if the vaccine might protect against penile and anal cancer.