TRENTON, N.J. -- An experimental vaccine to prevent the most common forms of cervical cancer has proved 100 percent effective in a two-year test on more than 10,000 girls and women, the drug maker
Merck is hoping to win Food and Drug Administration approval for the vaccine, Gardasil, and to put it on the market as soon as late 2006. It would be the first vaccine to prevent cervical cancer, a disease caused almost exclusively by a common sexually transmitted virus called the human papilloma virus, or HPV.
Doctors expect the vaccine to be offered to girls -- and boys because they can spread the virus to their partners. That effort is likely to run into opposition from conservatives and religious groups.
''I see this as a phenomenal breakthrough," said Dr. Gloria Bachmann, director of the Women's Health Institute at the Robert Wood Johnson Medical School in New Brunswick, N.J.
Worldwide, cervical cancer is one of the most common cancers among women. It kills almost 300,000 people a year, including about 3,700 in the United States. About 20 million Americans have some form of human papilloma virus, which in addition to cervical cancer can cause genital warts.
The genetically engineered vaccine prevents cervical cancer by blocking infection from the two strains of HPV that are reported to cause 70 percent of all cases of the disease.
The study included 10,559 sexually active women ages 16 to 26 in the United States and 12 other countries who were not infected with either of the two virus strains, called HPV 16 and 18. Half got three vaccine doses in six months; half received dummy shots.
Among those who were virus-free after the six months, none of those who received the vaccine developed either cervical cancer or precancerous lesions during two years of follow-up. This compared with 21 of those who had been administered the dummy shots.
''To have 100 percent efficacy is something that you have very rarely," said Dr. Eliav Barr, Merck's head of clinical development for the vaccine. ''We're breaking out the champagne."
The study, which was funded by Merck, will be presented today at a meeting of the Infectious Diseases Society of America, which is gathering in San Francisco.