The Cancer That Dare Not Speak Its Name

When you tell someone you have cancer, the first question you often hear is, "What kind?" Unfortunately, if it's anal cancer, the response may be "colorectal cancer," mumbled ambiguous words, or some other dodge. Discussion -- even mere mention -- of the anus is still considered taboo in many cultures, and this silence can be life-threatening, especially for people with HIV. But anal cancer is affecting more people every year. While the rate in the U.S. is not has high as other cancers, it is increasing at a rate of about 2% a year, and the National Cancer Institute expects 5,820 cases -- 3,680 women and 2,140 men -- to be diagnosed in 2011.

Certain groups are more likely to encounter anal HPV infection, which can lead to anal cancer. Though more women than men are diagnosed with anal cancer each year, some groups, such as HIV-positive men who have sex with men (MSM), have a significantly elevated risk of anal cancer. The social stigma that anal cancer carries with it prevents the open discussion and awareness needed to battle the disease, and stagnates funding to support research and care.

Human papillomavirus (HPV) is the most common sexually transmitted infection (STI) in the U.S. Over half the population will get it at some point in their lives. Each year 6 million people in the U.S. become newly infected with HPV, and 20 million people currently have the virus. While most HPV infections are resolved by the body's defenses, they cause half a million cases of cancer each year around the world.

A big misconception about HPV is that someone must be sexually promiscuous or have "casual sex" to contract the virus. Since HPV is a virus that is easily transferred, all it takes is one sexual partner to become infected. HPV is transmitted through skin-to-skin contact, including sexual intercourse. However, it can be transmitted by activity that does not include vaginal, oral, or anal intercourse. This includes deep kissing, genital skin-to-skin touching, and use of sex toys. Genital warts, which generally do not cause cancer but are caused by certain types of HPV, are transmitted in the same manner. In 90% of cases, the body clears the virus within two years without any treatment. But some patients, especially but not only those with weakened immune systems (such as people with HIV or organ transplant recipients) have difficulty clearing the virus on their own. If the HPV infection is persistent and caused by a high-risk (cancer-causing) strain of HPV, it can lead to cell abnormalities (also called dysplasia). Severe cases of dysplasia can lead to cancer over time.

While more women than men develop HPV-related cancers, HPV can cause anal, penile, and head and neck cancers in men. It can also cause cervical, vulvar, and vaginal cancer in women. According to the CDC, more than 20,000 HPV-related cancers occur in women and over 11,000 occur in men each year in the U.S. Worldwide, the World Health Organization documented 500,000 cases of cervical cancer alone and 260,000 related deaths in 2005.

There are about 150 types of HPV, with around 40 types transmitted through sex. Approximately 15 sexually transmitted HPV strains have the potential to cause cancer, and a person can be infected with multiple strains. Two strains, 16 and 18, cause around 70% of cervical and 85% of anal cancers. Most oral cancers are caused by type 16. Types 16 and 18 are also highly common in vaginal and penile cancer.

The Vaccines

There are currently two FDA-approved vaccines: Gardasil and Cervarix. Both protect against the two most common cancercausing strains, HPV-16 and HPV-18. Gardasil also protects against HPV-6 and HPV-11, which are linked to 90% of genital warts. Both use virus-like particles to enable the body to develop immunity to these strains of the virus. If a person is infected by HPV but has not been exposed to all four strains covered by the vaccine, it can still protect against the other strains.

The HPV vaccine is not mandatory in the U.S., but the CDC recommends that both men and women, and the parents of boys and girls, discuss the vaccine with their medical providers. In November 2011, the CDC amended its policies to recommend that both boys and girls be routinely vaccinated against HPV. Vaccination allows both sexes to take a proactive step toward protecting themselves and their partners from the virus and its potential consequences. Since HPV is easily transmitted, vaccinating against the virus before a person becomes sexually active offers the most protection. Even after sexual activity has started, however, a person may still get protection from the vaccine.

The FDA has approved Gardasil to prevent vulvar, vaginal, and cervical cancer in women, and anal cancer and genital warts in men and women. It is approved for use in males and females ages 9-26. It is routinely recommended for girls and boys, with a target age of 11-12. "Catch-up" vaccination is routinely recommended for women in the 13-26 year age range and in men aged 13 to 21 years. The vaccine is also recommended for men aged 22 to 26 years, but the recommendation in this group is "permissive" and not "routine", meaning that men may not have it covered by their insurance. The FDA has also approved Cervarix to prevent cervical cancer. It is approved for girls ages 9-25. Recent studies suggest it may also protect against anal HPV infection, which can lead to anal cancer.

To date, HPV vaccination rates in the U.S. have been very low: a 2010 CDC report showed that only 32% of females aged 13 to 17 received the full three-shot course of the vaccine. By comparison, countries such as Australia and the United Kingdom have rates that are double or more than the U.S. (partially due to school vaccination programs). While all countries with access to the vaccine will see a decrease in HPV-related cancers, those with more people vaccinated will see a sharper reduction in these cancer rates. Mistaken concerns that vaccinating adolescents against a common STI will encourage early sexual activity may be partly to blame for the slow ramp-up of vaccinations in the U.S. Others have cited concerns about possible side effects as a reason to delay vaccination, but the FDA and the CDC continuously evaluate the vaccines' safety and have determined that both vaccines are safe.

Vaccination is by far the best way to prevent HPV infection. But further steps should be taken to prevent HPV-related diseases, even in vaccinated persons. Some people may already be infected with HPV before getting vaccinated, while others may contract an HPV type not covered by the vaccine.

While having just one sexual partner can expose you to HPV, fewer partners can reduce your risk of being infected with the virus. Of course, one can still contract the virus with just one partner. Although condoms can reduce the risk of HPV infection, they are not entirely effective because HPV can be transmitted through skin surfaces not covered by the condom or during sexual activity that occurs before the condom is used.