One of the most astounding scientific realizations of the last 50 years was that cancer could be an infectious disease--specifically, one caused by the human papillomavirus, or HPV. There are more than 100 types of HPV, at least 30 of which are spread by sexual contact. HPV has been linked to certain types of skin cancers as well as:
Some scientists have estimated that as many as five percent of all human cancers can be linked to HPV infection!
HPV is an extremely common virus. More than 50 percent of sexually active adults are thought to be infected with at least one strain of the virus, and up to 80 percent of sexually active women will have been exposed to the virus by the time they turn 50.
Most people with HPV will never have any symptoms. Others will have one or more outbreaks of genital warts, experience pre-cancerous cervical changes, or even develop one or more HPV-related cancers. Because so many people who are infected will never have problems associated with the virus, doctors do not generally screen for HPV.
Simply knowing you have tested positive for a strain of the HPV virus does not mean you will definitely get cancer, or genital warts, it just means that you have been exposed to the virus and are at risk. In fact, research has shown that the majority of infected individuals will clear the infection within 2 years on their own.
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Consequences of HPV
Before the mid 1980s, the idea that people could transmit cancer to each other was considered ludicrous by most people in the medical research field. However, as evidence piled up and research techniques began to improve, people slowly became convinced.
It is now widely accepted that HPV causes an estimated 99 percent of cervical cancers. In early 2007, a prestigious medical journal published a paper suggesting that HPV may also be responsible for increases in mouth and throat cancer cases. The main causes of these cancers have historically been smoking and use of oral tobacco.
Cervical cancer was once the leading cause of cancer-related death among women in the U.S. Though the number of American women dying from the disease has decreased do to an increase in regular Pap smears, it is still the fifth leading cause of cancer-related death among women worldwide.
No woman should ever have to die of cervical cancer. Regular Pap smears can detect HPV-induced changes to the cervix early, when they are still very treatable. However, there are women who do not get tested regularly. This is particularly a problem among women in low resource countries and low-income communities, and among women who have passed their childbearing years. One of the main motivators for women to go to a gynecologist is the need for birth control pills, and many stop seeking regular preventative care once they no longer need their prescription. HPV can lie dormant for many years before causing cancerous changes to the cervix. It is important that women continue to get regular Pap smears throughout their lifetimes.
Scientists are increasingly focused on preventing HPV. HPV is spread by oral sex, vaginal sex, and anal sex, as well as by skin-to-skin contact with infected areas. Since the virus is spread from skin to skin, not just through body fluid, it is possible to transmit the virus even when a condom is used. Condoms do, however, reduce the risk of transmission. The high prevalence of the virus, combined with the fact that condoms don't offer complete protection, has prompted scientists to research alternate methods of prevention. One of the avenues they are exploring is vaccines.
Multiple vaccines for the most common cancer and genital wart-causing HPV strains are either in development or already on the market. However, because HPV is a sexually transmitted virus, discussion about these vaccines has frequently become a political rather than a scientific debate. Vaccines are most effective before a person has been exposed to the virus, but many parents and politicians are resistant to the idea of vaccinating young girls for a sexually transmitted disease for fear that it might encourage them to have unprotected sex.
A far greater concern for most, however, is that women who have gotten the vaccine may stop seeking regular Pap smears. These vaccines only protect against the most common HPV strains, and they don't protect woman who have already been exposed to HPV. Therefore women still need to follow the recommendations for regular Pap smears--it just becomes less likely that they'll have a positive test.
- Debate: Should States Mandate the HPV vaccine?
- Can Gardasil (the HPV vaccine) Give Me Cancer?
- Does the HPV Vaccine Work in Men?
- Is Gardasil Safe?
Neilson, C.M. et al."Consistent Condom Use Is Associated with Lower Prevalence of Human Papillomavirus Infection in Men" The Journal of Infectious Diseases 2010;202:445-451
The CDC HPV Fact Sheet Accessed 6/14/07
The World Health Organization Cancer Fact Sheet Accessed 6/14/07
Wright JD, Herzog TJ."Human papillomavirus: emerging trends in detection and management." Curr Womens Health Rep. 2002 Aug;2(4):259-65.
Stanley MA, Winder DM, Sterling JC, Goon PK. HPV infection, anal intra-epithelial neoplasia (AIN) and anal cancer: current issues. BMC Cancer. 2012 Sep 8;12:398.
Stoler MH. "A brief synopsis of the role of human papillomaviruses in cervical carcinogenesis." Am J Obstet Gynecol. 1996 Oct;175(4 Pt 2):1091-8.