US drug manufacturer Merck & Co has claimed a study of an experimental vaccine to prevent cervical cancer has found it to be 100 percent effective in the short term at blocking the disease and lesions usually likely to turn cancerous.
Gardasil, a genetically engineered vaccine, blocks infection with two of the 100-plus types of human papilloma virus, HPV 16 and 18. The two sexually transmitted viruses together cause about 70 per cent of cervical cancers.
The final-stage study of Gardasil included 10,559 sexually active women ages 16 to 26 in the United States and 12 other countries who were not infected with HPV 16 or 18. Half got three vaccine doses over six months; half got dummy shots.
Among those still virus-free after the six months, none who received the vaccine developed cervical cancer or precancerous lesions over an average two years of follow-up, compared with 21 who got dummy shots.
The study, which was funded by Merck, is to be presented tomorrow at a meeting of the Infectious Diseases Society of America.
A second analysis, including hundreds more women participating in the ongoing study, showed that after just one dose the vaccine was 97 per cent effective.
That analysis found only one of the 5,736 women who got the vaccine developed cervical cancer or precancerous lesions, compared with 36 among the 5,766 who got dummy shots.
Cervical cancer is the second-most common cancer in women and the second-ranked cause of cancer deaths, resulting in about 3,000 deaths in the United States and nearly 300,000 around the world each year.
At least half of sexually active men and women become infected with genital HPV at some point.
AP