FAQ: human papillomavirus

The major cause of cervical cancer is human papillomavirus (HPV), which is typically transmitted through sexual intercourse. A vaccine for certain types of HPV has recently been introduced and is offered to young women. The following information will tell you more.

It's a good idea. Recent studies suggest that testing for HPV, the virus that causes cervical cancer, may be more sensitive than the Pap test, though it also produces more false positives. In a study published in the New England Journal of Medicine, the HPV test detected 94.6 percent of abnormal growths, far outpacing the Pap smear, which detected only 55.4 percent. The HPV test had a slightly greater chance of producing a false-positive result.

Having both tests may be the best bet: in the study, combining the tests was 100 percent effective in detecting precancerous growths. Some women now request — and many doctors automatically administer — both tests.

Yes. Although the HPV vaccine is very effective, it doesn't offer 100 percent protection against cervical cancer. A vaccine called Gardasil that prevents HPV infection and genital warts is now available in Canada, the United States and a number of other countries. Other vaccines are on the way. Gardasil is most effective if a person is not already infected with HPV; it is currently approved for girls and women aged nine to 26. Gardasil guards against only four strains of HPV. Two of these strains are responsible for 70 percent of cervical cancer cases, while the other two are responsible for 90 percent of genital warts.

Although Gardasil is a powerful defense against cancer, women who have been vaccinated remain vulnerable to other HPV infections. What's more, women who were sexually active before being vaccinated may have already been exposed to HPV. For these reasons, women who have been vaccinated still need Pap smears.