Vaccine May Prevent Cervical Cancer
Feb. 20, 2001 -- One day it may be possible to immunize people against a sexually transmitted virus that is the main cause of cervical cancer in women.
Surprising as it sounds, researchers say now that they know that most cervical cancers are caused by the virus, they are working on ways to protect against it with a vaccine. If the vaccine research continues to be as promising as scientists predict, immunization eventually could be offered to sexually active teenagers and others at high risk for getting and passing on sexually transmitted diseases (STDs).
"If the vaccine were shown to be safe and effective when administered to a much larger group of people, my assumption would be that you could immunize both men and women because it would be in principal more effective to try to interfere with infection before they are exposed to the virus," says Douglas R. Lowy, MD, of the National Institutes of Health in Bethesda, Md.
In a paper published in the Feb. 21 issue of the Journal of the National Cancer Institute, Lowy and colleagues describe the results of a study in which 72 women and men received either the experimental vaccine or a placebo injection.
The vaccine is designed to help the recipient build immunity against human papillomavirus (HPV) -- which is best known for causing genital warts. One particular type of HPV, known as HPV16, is now thought to be responsible for approximately half of all cases of cervical cancer.
Lowy's study showed that people who received the experimental vaccine made up to 40 times more protective antibodies against the HPV16 virus than those who received only the placebo injection. Although the study included only 14 men, Lowy says offering the vaccine to men will probably be important in future research as scientists focus on the most effective way to prevent HPV infections from spreading. For now, this study is the first to show that protection in the form of a vaccine is possible.
In an editorial accompanying the study, Harold zur Hausen, MD, of Heidelberg, Germany, says an effective vaccine against HPV "could theoretically prevent more than 300,000 cervical cancer cases per year worldwide."
Many women who are infected with HPV don't know it, and studies show that the average woman is infected for about 10 years before cervical cancer develops, says Hildegund C.J. Ertl, MD, PhD. "Most women when they get infected with the [HPV] virus simply get rid of it, but there is a small fraction of women that don't, and they become persistently infected," says Ertl, a professor and vaccine researcher at the Wistar Institute in Philadelphia.
She says the new vaccine research is a promising first step but cautions that it will be years -- probably as many as 10 years -- before an actual vaccine is available to the public. Right now, the experimental vaccine being used in the studies only protects against HPV16, but there are three other types of HPV that also have been linked to cervical cancer. Lowy says his group will continue to do studies with the vaccine that protects against the most common type and may eventually expand it to protect against the others.