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The Dallas Morning News
(KRT)
WASHINGTON - A new vaccine may not only protect women from cervical cancer, but also the much more common problem of genital warts.
The vaccine trains the body's immune system to fight two types of human papillomavirus, or HPV, responsible for about 70 percent of cervical cancers. Data released earlier this year found that vaccinated women did not develop any lesions that can signal the beginnings of malignancy.
But the new data, which involve more than 5,000 women, also examine the vaccine's effectiveness against two types of HPV that cause genital warts. No women who were fully vaccinated developed warts about two years later, compared with about 40 cases in women who only got placebo shots.
"This vaccine is safe, it is tolerated, and it is 100 percent effective," said Dr. Diane Harper of Dartmouth Medical School. She presented the study results in Washington, D.C., during an annual infectious disease meeting sponsored by the American Society for Microbiology.
The results for potentially cancerous lesions among those same women were similar: No cases among those who were fully vaccinated, with 37 cases among those in the comparison group.
However, there are still unanswered questions about the vaccine. Chief among them is how long the immunity against HPV might last, said John Schiller of the National Cancer Institute. Scientists will continue to follow the women in the study for at least five years to see whether the vaccine continues to maintain its high effectiveness or causes any unanticipated side effects.
The study's sponsor, manufacturer Merck & Co., is not waiting for those results to seek approval. This month, it filed for approval of the vaccine under the name Gardasil.
A second vaccine called Cervarix, manufactured by GlaxoSmithKline, is also in advanced clinical trials and has boasted similarly strong results. New data presented Saturday in Washington reported this vaccine produced a stronger immune response among girls ages 10-14 than in older ages. The finding implies that there may be greater benefit in vaccinating adolescents, with the hope of protecting them throughout adulthood.
HPV is a sexually transmitted virus. About 80 percent of women will become infected with HPV by the time they are 50, although only a tiny fraction will develop cancer.
Rates for cervical cancer in the United States have plummeted through the regular use of Pap smears. Nonetheless, about 3,700 women are predicted to die from it this year. Cervical cancer rates in poorer countries, where women do not have good access to health care, remain much higher.
Genital warts, though not lethal, are a much more common problem. About 300,000 new cases occur each year.
All the women in the new study were young - ages 16 to 23 - and not infected with HPV at the beginning of the study. It is not known whether the vaccine could protect men or older women already infected.
Though the HPV vaccine could drive cervical cancer rates even lower, it will not replace the Pap smear, Schiller said. Some strains of cancer-causing HPV are not contained in the vaccine. However, the vaccine may reduce the numbers of abnormal smears, which are a psychological burden to women and to add to health care costs.
The extraordinary effectiveness of the two HPV vaccines has surprised even those who have closely followed their development, Schiller said.
"It's beyond our wildest expectations," he said. "We're very excited."
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(c) 2005, The Dallas Morning News. Distributed by Knight Ridder/Tribune News Service.
