Pulse
Sure Shot
A new vaccine may soon reduce the threat of cervical cancer.
Each year, about 5.5 million women in the United States are diagnosed with sexually transmitted human papillomavirus (HPV), and a total of 20 million are infected at any given time.
Although most women recover from the virus within six months, those who do not are at far greater risk of getting cervical cancer—a disease that was diagnosed in approximately 11,000 women in the United States in 2004 and that killed nearly 4,000 that same year, according to the American Cancer Society. “If we do sensitive testing of cervical cancer, almost 100 percent of cases will have some evidence of HPV,” says Levi Downs, M.D., assistant professor of obstetrics, gynecology, and women’s health in the University of Minnesota’s division of gynecologic oncology. “That makes this virus a pretty valuable public health target.”
Human papillomavirus may have met its match, however. For the past two decades, researchers have been attempting to develop a vaccine that would protect against the virus. Most recently, researchers from Dartmouth Medical School in Hanover, New Hampshire, led an international randomized, placebo-controlled study to assess the effectiveness and safety of a vaccine that prevents persistent infection caused by HPV-16 and HPV-18, two types of HPV that account for 70 percent of cervical cancers. The women who completed the study and received the appropriate number of vaccines were found to be 100 percent protected against persistent infection, according to results published in the Nov. 13, 2004, issue of The Lancet.
Such potent findings have caught the attention of Downs, who specializes in HPV research and has spearheaded efforts to designate the University of Minnesota as one of 35 sites in the United States for the next phase of the study. Downs hopes results of the study, called the international Papilloma Trial to Prevent Cervical Cancer in Young Adults (a.k.a., PATRICIA), will lead the Food and Drug Administration to approve the vaccine.
Nationwide, approximately 4,000 girls and women ages 15 to 25 will take part in the study. Downs estimates 150 of them will come from the University of Minnesota. Participants will be randomized and will receive either the HPV vaccine or the hepatitis A vaccine (control group). The women will be given three vaccinations—the first immediately upon enrollment, the second, one month after the first dose, and the third six months later. Study participants will be followed for five years. “We know that the efficacy of the vaccine lasts at least four to five years,” says Downs. “As we continue to follow vaccinated women out [past the time of the vaccination], we will be able to determine if we really do need to revaccinate them that often or if they are protected for even longer periods of time.”
If the results of PATRICIA demonstrate the safety and efficacy of the vaccine, it could be available to the public as early as 2008. Because the HPV infections that end up causing cancer occur most often during puberty, the vaccine will likely be given to girls between the ages of 10 and 15. Downs does not downplay the potential for the vaccine. “It may seem crazy to say, but if this vaccine works, and they are able to implement it worldwide, it could do to cervical cancer what other vaccines have done to polio and smallpox,” he says. “It could essentially eradicate the disease entirely … and that is not an overstatement.”—J. Mettner