Who would imagine that a virus was the cause of certain types of cancer? It’s beyond conjecture now because research has shown that the connection is definite. Human papilloma virus, or HPV for short, has been identified as the major player in cervical cancer, and women all over the world can benefit from new knowledge about this most common sexually transmitted disease. For many years, medical researchers have known about the HPV – cancer connection, but until recently there was little ability to affect the disease process. Now, with a newly released vaccine to target the specific strains of HPV known to be most responsible for cervical cancer, there is finally a weapon with which to fight. But what is this virus exactly, and why will a vaccine decrease the incidence of cervical, vaginal and vulvar cancers?

HPV is actually a group of common skin viruses of which there are over one hundred known strains. Most people are familiar with plantar warts, and these are caused by a specific HPV strain. Genital warts are caused by at least four different strains, and cervical cancer is linked most strongly with two particular strains, HPV 16 and 18. These are known as “high risk” forms of the virus, and they are the specific targets of the currently available vaccine.

The virus is passed from person to person through skin-to-skin contact, and the cervix is particularly vulnerable to attack because of the constant turnover of cells – virtual DNA heaven. Once the virus insinuates its own DNA into the cervical cells, a sequence of events can lead, over months to years, to precancerous changes. These changes can be detected on a Pap test or cervical biopsy, but the changes are otherwise silent. There is no telltale vaginal discharge or pain to herald the viral activity, and therefore, both male and female partners are generally unaware of its presence. Condoms are not fully protective because there is incomplete coverage of all potentially vulnerable genital skin. In some cases, the virus does not become active right away and can literally hide within the cells. There are known risk factors such as smoking or immunosuppression that can hasten (and worsen) the viral effects, but for the most part, it seems random as to which individuals will express the HPV changes and when.

The HPV vaccine will ideally target young males and females before they become sexually active. It is not enough to vaccinate only girls and women; however, females definitely bear the brunt of the adverse effects of this infection. Health care providers will need to use specific guidelines and their own judgment when it comes to administering the vaccine, and they will need to counsel patients regarding the limitations of this vaccine including the fact that it will not prevent any other sexually transmitted diseases such as HIV. Several injections would be required over the course of months, similar to the hepatitis B vaccine, in order to confer immunity; but the effort will be well worth it. Greater than 50 percent of Americans have been/will be infected with HPV by age 50; however, only a very small percentage of women will develop cervical disease. Most of those, perhaps as many as 90%, will exhibit mild cervical change that are cleared by the immune system over the course of a few years. That leaves 10% of women who can develop persistent disease that may progress to severe precancerous changes and ultimately to cervical cancer.

Women with a history of multiple sex partners, sexual activity at a young age, smoking, poor nutrition and substance abuse have a higher propensity to develop HPV infection and cervical disease. The effect of multiple partners is obvious, but the relationship of tobacco use and the development of cervical disease are complex and relate to damaged DNA. But even with the elimination of all the known risk factors, it takes only one sexual partner to impart a high-risk strain. For this reason, all women should avail themselves of the simple screening tool known as the Pap test.

Since its development in the late 1940’s, the Pap test has certainly saved many lives from invasive cervical cancer. It meets all the criteria for a great screening test including affordability, sensitivity to disease detection and specificity to cervical cell abnormalities. The Pap test has become a routine part of a woman’s annual GYN exam, and over the years, more accurate methods of specimen collection and analysis have been developed. Still, like any test, it has occasional lapses in accuracy, so putting it off for years at a time is unwise. The exact interval of screening and when to start screening may vary slightly from woman to woman depending upon her individual risk factors. All women should begin screening by age 21 or within three years of becoming sexually active – whichever comes first.

The development of the HPV vaccine is clearly a step forward in the fight against cancer, and you should consult your healthcare provider as to whether or not you and/or your children are candidates to receive it. Once received, it should not be viewed as a substitute for obtaining routine physicals and Pap tests. It will undoubtedly take time to see the ultimate desired effect of lowering or virtually eliminating cervical cancer, and in the meantime, women need to continue to be vigilant and make every effort to lower their risk factors.

This article, authored by Jacqueline Thompson, MD, FACOG, appears in Radius magazine, Fall 2006. You can read more about Dr. Thompson and find additional health information at the Radius website www.radthemag.com.