March 10, 2010
Researchers from Costa Rica have reported that women over the age of 40 are not likely to benefit from vaccination to prevent human papillomavirus (HPV). The details of this study were published in the March 3, 2010 issue of the Journal of the National Cancer Institute.
Human papillomaviruses consist of more than 100 different viruses. Some types of HPV cause warts on the hands or feet; others cause genital warts; and some have been linked with cancer, most notably cervical cancer. The types of HPV most commonly linked with cervical cancer are HPV16 and HPV18, but several other high-risk types contribute to cancer as well.
The types of HPV that cause cervical cancer or genital warts are transmitted sexually. HPV infection is extremely common and generally occurs soon after an individual becomes sexually active. Although most infections resolve on their own, some persist and can lead to precancerous or cancerous changes to the cervix, vulva, vagina, penis, and anus. HPV infection has also been linked to certain cancers of the head and neck.
Recognition of the link between HPV and cervical cancer led to the development of vaccines designed to prevent infection with certain high-risk types of HPV.
Currently, there are two vaccines approved for the prevention of HPV 16 and 18: Gardasil® and Cervarix®. Gardasil also protects against HPV 6 and 11, which are associated with most types of genital warts. The vaccines are recommended for girls as young as age 9 and up to age 26. It is generally agreed that vaccination of older women would be of little benefit. A previous study conducted by the Researchers from the Harvard School of Public Health reported that HPV vaccination for prevention of cervical cancer is not cost-effective in women between the ages of 35 and 45 years.
A study of more than 9,000 Costa Rican women ages 19 to 97 evaluated the patterns of HPV infection as women age. These researchers found that the rate of newly detected infections declined with age—from 35% in women ages 18-25 to 13.5% in women over the age of 42. In both younger and older women, new infections typically cleared up without treatment within two years. They found that new infections typically did not progress to worse disease in older women.
Based on their findings, the researchers concluded that HPV vaccination was not likely to be beneficial for older women. The vaccinations are used to prevent new infections, and older women are not getting many new infections.