Thursday, November 21, 2002

Experimental Vaccine Protects Against a Virus Linked to Cervical Cancer, Study Finds By LILA GUTERMAN In tests involving nearly 2,400 college-age women, an experimental vaccine prevented infection with a virus linked to cervical cancer, researchers report today in The New England Journal of Medicine. The vaccine protects against human papillomavirus type 16 (HPV-16). Approximately 20 percent of adults become infected with that sexually transmitted virus, which is present in half of all cervical cancers. Four other types of human papillomavirus are thought to be responsible for most of the rest. According to Christopher P. Crum, director of women's and perinatal pathology at Brigham and Women's Hospital, in Boston, more than 450,000 cases of cervical cancer are diagnosed every year, and almost 250,000 women die of it yearly. Most women who become infected with any strain of human papillomavirus do not get cancer or even experience abnormal Pap smears. That's because the body's immune system normally attacks and clears the virus. Since HPV-16's discovery, in 1983, researchers have hoped that a vaccine could strengthen the immune response and prevent persistent infections in all women. Scientists led by Laura A. Koutsky, a professor of epidemiology at the University of Washington at Seattle, recruited 16-to-23-year-old female volunteers at 16 sites, most of them universities. Of the women, 1,533 were not already infected and were the primary subjects of the study. Half of the women received a vaccine consisting of particles that mimic the shape of the virus, while the other half received a placebo. (The women who were already infected also received either the vaccine or the placebo, but the journal paper did not report on them. Ms. Koutsky says the vaccine is not intended to treat already-infected women.) The experimental vaccine was produced by Merck Research Laboratories, which also financed the trials. During semi-annual testing of the women over a year and a half, the researchers discovered that 41 women had repeated infections with HPV-16, including 9 who had precancerous spots. All of those women received the placebo. "This is all you could ask for" in a vaccine, said Dr. Crum, who wrote an accompanying commentary in The New England Journal about the trials but was not involved with them. (Seventy-four women tested positive for infection only once; those infections presumably cleared up. That group included six women who received the vaccine.) Christine M. Peterson, director of gynecology at the University of Virginia's student-health center and an assistant professor of obstetrics and gynecology, said that a vaccine would be most welcome in a collegiate setting. She cited a study that found that 15 to 20 percent of college women are infected with some form of human papillomavirus. "About 10 percent of Pap smears that we perform here have an abnormality due to human-papillomavirus infection," said Dr. Peterson, who ran trials at Virginia as part of Ms. Koutsky's study. Further trials are required before the vaccine can gain approval for public use. Ms. Koutsky is running trials of another Merck vaccine that is intended to protect against HPV-16 as well as three other virus types, HPV-6, HPV-11, and HPV-18. In his journal commentary, Dr. Crum estimated that a vaccine covering just HPV-16 and HPV-18, given to girls before they become sexually active, could reduce death from cervical cancer by 95 percent. "We could, in our lifetime, see the gradual but progressive dismantling of the barriers to preventing cervical cancer," he wrote. Easy-to-print version E-mail this article

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