HPV facts
Cervical cancer and the new vaccine
By Dawn Stapleton
Sarah Feldman, MD, MPH, is researching HPV to improve prevention methods and treatments for cervical cancer.
For more than a century, vaccines have aided humankind in staving off debilitating and even deadly illnesses, from smallpox and rubella to polio and the flu. Last year, the Food and Drug Administration (FDA) approved another inoculation, one that protects against the human papillomavirus, or HPV, some strains of which cause cellular changes that can lead to cervical cancer.
The vaccine immunizes patients against two of the most common types of HPV responsible for cervical cancer, as well as two others that cause many cases of genital warts. However, roughly 30 percent of cervical cancers are caused by other HPV subtypes not covered by the current vaccine. Further, it is not effective in protecting girls or women who have already been exposed to the virus, or who subsequently are exposed to one of the noncovered HPV types. Thus, even those who receive the vaccine will not be completely protected against cervical cancer and its precursors.
The FDA recommends that 11- to 12-year-old girls be vaccinated to safeguard them before any type of sexual activity begins, though the vaccine is approved for use in girls as young as 9 and women as old as 26. Inoculation requires that three doses be administered over the course of 12 months.
Though the new vaccine offers protection to some women, there are additional uncertainties, such as how long its protective effects last, since it has only been studied for two to three years in any one woman. Physician-scientists in Dana-Farber's Women's Cancers Program intend to study this and other questions through the new Pap Smear Evaluation Center Database that is currently being established at the Dana-Farber/Brigham and Women's Cancer Center (DF/BWCC) to track patients' progress.
Among the lingering questions are: Is it useful to test women with HPV to see which subtypes they have been exposed to? Should any woman over 26 be vaccinated? Could the vaccine help women who have already been exposed to HPV?
While researchers strive to find more answers, some state legislatures are moving to make the HPV vaccine mandatory in accordance with FDA guidelines.
"For all we know, the vaccine could be a lifelong preventive, or girls and women may need periodic boosters: More studies are required," says Sarah Feldman, MD, MPH, director of the Pap Smear Evaluation Center at DF/BWCC. "What is clear from statistics is that 77 percent of adolescents (male and female) in the U.S. have already been exposed to high-risk subtypes of HPV and that teens report sexual activity at earlier ages, often as young as middle school. In order to be effective, it is essential that the vaccine reach girls before the onset of sexual activity, and that they are appropriately screened for precancerous cervical changes due to other HPV infections or to a waning of the vaccine's effectiveness."
- Next: What we know
- Page: 1 | 2 | 3
