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The human papillomavirus (HPV) occurs in approximately 70 percent of all women. Most women who are infected by HPV simply get over it. Those women who are not able to fight off the virus are at risk for developing cervical cancer.
In the United States, Pap smear screening followed by treatment of precancerous cervical lesions prevents most cases of cervical cancer linked to HPV. In the rest of the world, where screening and treatment are less available, cervical cancer is the second leading cause of cancer-related death among women.
A research group established 10 years ago at the UW has worked to find better ways to detect and prevent cervical cancer. Dr. Laura Koutsky, professor of epidemiology at the UW's School of Public Health and Community Medicine, was the principal investigator in a study that found that a new vaccine shows promise in preventing a specific type of HPV.
The vaccine, developed by Merck Research Laboratories, appears to prevent infection with HPV-16, a common type of the virus that infects about 20 percent of the world's adult population. There are more than 100 types of HPV.
The study involved almost 2,400 women. Of that group, 41 women who received a placebo tested positive for HPV-16 during the study, while no infections were found in the women who received the vaccine. The vaccine appears to prevent HPV from lingering in the genital tract where it can cause lesions and be transmitted to a sexual partner. The results of the study were published in the Nov. 21, 2002, issue of The New England Journal of Medicine. More studies will be needed to confirm these initial promising results.
Dr. Nancy Kiviat, another member of the UW research group, is chief of pathology at Harborview Medical Center, director of the UW's cytopathology service, and a professor of pathology. Koutsky and Kiviat have worked together on cervical cancer control for more than 20 years in impoverished areas of the world, such as West Africa, as well as in the United States. They are trying to discover novel approaches to identify women at risk and then prevent the disease.
It's not by accident that Kiviat joined the staff at Harborview.
"Harborview serves those who would otherwise be unserved by the medical system," she said, "and that means we see many patients who have not undergone the regular Pap screening that is key to preventing cervical cancer."
A normal human body has controls to ensure that, when a cell divides, only those daughter cells without mistakes in their DNA replication are allowed to survive. HPV interrupts this natural system of checking for and destroying faulty cells. As a result, mutations can continue to replicate and grow. Healthy bodies often can rid themselves of the virus quickly and stop the production of mutations. Individuals with suppressed immune systems, however, are more vulnerable.
According to Kiviat, HPV presents the greatest risk in populations with a high incidence of HIV/AIDS, as is the case in West Africa. Because HIV suppresses the body's immune system, individuals with HIV cannot fight off HPV. It is for these populations, where screening and treatment for HPV are rare, that the design of a vaccine to prevent HPV infection is critical.
Kiviat said her interest turned to West Africa because both HIV 1 and HIV 2 are prevalent there. The progress of HIV 2, which is found primarily in West Africa, India and Portugal, is much slower than HIV 1. Individuals with HIV 2 can live for 20 or 30 years with the infection.
Said Kiviat, "The point is, if people are able to live with HIV, you don't want them to die of cervical cancer. An effective HPV vaccine could extend many lives in these parts of the world."
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