HPV vaccine 'may significantly' lower cervical cancer risk, study finds

Sept. 30 (UPI) -- Women vaccinated against HPV may be at significantly lower risk for developing cervical cancer, according to a study published Wednesday by the New England Journal of Medicine.

Girls who received the shot before turning 17 reduced their risk of cervical cancer by 88% compared to unvaccinated women, while women inoculated against the virus between ages 17 and 30 cut their risk in half, the data showed.

"HPV vaccination is protective not only against cellular changes that can be precursors to cervical cancer, but also against actual invasive cervical cancer," study co-author Jiayao Lei said in a statement.

"[This] is something we have long suspected," said Lei, a researcher at the Department of Medical Epidemiology and Biostatistics at Karolinska Institute in Sweden.

The most common sexually transmitted infection in the United States, HPV, or human papillomavirus, is a group of viruses that can cause genital warts and different types of cancer -- including cervical cancer, which kills more than 250,000 women per year worldwide.

The U.S. Centers for Disease Control and Prevention recommends HPV vaccination for all children aged 11 or 12 years, although those as young as 9 can receive the shot.

Earlier research has shown that HPV vaccine protects against HPV infection, genital warts and precancerous cervical lesions that could develop into cervical cancer, according to the National Cancer Institute.

Little is known, however, about how well the shot protects against the development of "invasive" cervical cancer. The cancer spreads from the surface of the cervix to tissue deeper in the cervix or to other parts of the body, making it the most severe form of the disease.

For their study, the researchers followed nearly 1.7 million women aged 10 to 30 years, over a period of 11 years.

Of these women, 500,000 were vaccinated against HPV, the majority before the age of 17, the researchers said.

Nineteen vaccinated women were eventually diagnosed with cervical cancer, while the disease was diagnosed in 538 unvaccinated women, the data showed.

"Girls vaccinated at a young age seem to be more protected, probably because they are less likely to have been exposed to HPV infection and given that HPV vaccination has no therapeutic effect against a preexisting infection," study co-author Par Sparen, also of the Karolinska Institute, said in a statement.

"HPV vaccination may significantly reduce the risk of cervical cancer, especially if completed at an early age," Sparen said. "Our data strongly supports continuing HPV vaccinations of children and adolescents through national vaccination programs."