A five-year, multi-site international study has shown that human papillomavirus (HPV) vaccinations given to adolescents and young women decrease the number of abnormal Pap smears, biopsies and cases of genital warts.
Since some of these genital abnormalities are identified as precursors to cancer, it is anticipated that these findings will eventually translate into lower rates of cervical, vulvar and vaginal cancers.
HPV is one of the most common sexually transmitted infections. Although most infections will clear up without intervention, some infections with low-risk HPV (types 6 and 11) can cause genital warts and abnormal cervical cells, while high-risk types of HPV (types 16 and 18) can progress to cancers of the cervix, vulva or vagina.
“Cervical cancer is the second leading cause of cancer death in women worldwide, right behind breast cancer in women,” says Kevin Ault, MD, associate professor in the Department of Gynecology and Obstetrics, Emory University School of Medicine, and a co-investigator on this study. “This vaccine has been shown to reduce the number of biopsies and painful treatments in women, while also reducing cancer risks in a woman’s life.”
The researchers studied 17, 622 women aged 15 to 26 years who were enrolled in one of two randomized, placebo-controlled, efficacy trials for the vaccine targeting HPV types 6, 11, 16 and 18 (known as a quadrivalent vaccine). Women in one group were uninfected with HPV (negative to 14 HPV types), while another group had a mixed population of HPV-exposed and -unexposed women (intention to treat group). All women underwent cervicovaginal sampling and Pap testing.
In the group that was uninfected with HPV, vaccination was up to 100 percent effective in reducing the risk of HPV 16/18-related high-grade cervical, vulvar and vaginal lesions and of HPV 6/11-related genital warts. In the mixed group, vaccination was statistically significant in reducing the risk of any high-grade cervical, vulvar and vaginal lesions, genital warts, Pap abnormalities and cervical therapy, irrespective of HPV type.
“The HPV vaccine is specifically designed to prevent cancer in its earliest stages,” says Ault. “Researchers were aware of the tight link between HPV and cancer, which helped in the development of this vaccine.”
Ault continues, “Many of the treatments for HPV today can cause problems later in life for pregnant women, which can lead to premature delivery of their babies. We hope getting this vaccine during a woman’s younger years will prevent those complications, as well.”
The U.S. Food and Drug Administration approved the preventative vaccine, known as Gardasil, in 2006 for use in females nine to 26 years of age. To date, there is no vaccine specifically designed to treat HPV, once infected.
With this data now complete, the researchers are looking at the possibility of second-generation vaccinations for more types of HPV not covered by the quadrivalent vaccine.