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HPV Vaccines Hold Promise for Reducing Cervical Cancer
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Each year, the editors of the general medicine version of Journal Watch pick the past year's top stories. Typically, these stories emerge from a group of articles, rather than from a single study. We have included links to Journal Watch summaries and other materials that are freely available on the web.
During their lifetimes, as many as 70% of sexually active women become infected with human papillomavirus (HPV), which is responsible for virtually all cases of cervical cancer and genital warts. Worldwide, HPV infection causes almost 500,000 cases of cervical cancer and 280,000 deaths annually. Although most deaths occur in developing countries, where screening and treatment programs are not routine, cervical cancer also kills about 35,000 women in Europe and North America yearly. HPV types 16 and 18 cause about 70% of cervical cancer and high-grade cervical intraepithelial neoplasia (CIN) cases, and types 6 and 11 cause 90% of anogenital warts.
Genuine excitement has arisen about the apparent success, in phase 2 and 3 trials, of vaccines (produced by two different pharmaceutical manufacturers) that prevent HPV infection. In one randomized study, more than 1100 young women (age range, 15-25) without histories of HPV infection or abnormal cervical pathology received either three doses of HPV vaccine (against types 16 and 18) or placebo (Journal Watch Dec 7 2004). Vaccine recipients were significantly less likely than placebo recipients to develop incident HPV type 16 or 18 infections (0.6% vs. 6.5%), persistent infections (0% vs. 2%), or abnormal cervical cytology (0.4% vs. 4.9%) during as long as 27 months of follow-up.
In another randomized double-blind study, more than 550 young women received three doses of quadrivalent vaccine (against types 6, 11, 16, and 18) or placebo during 6 months (Lancet Oncol 2005 May; 6:271). During 36 months of follow-up, the combined incidence of persistent infection or disease decreased by 90% among those who received active vaccine compared with those who received placebo. Editorialists have noted that worldwide vaccination of young women and simplified approaches to screening (using HPV DNA testing) offer the promise of virtually eradicating cervical cancer (New Engl J Med 2005 Nov 17; 353:2101). Without new approaches to intervention, deaths from cervical cancer could increase by fourfold, to a million annually by 2050, with most in developing countries.
The promise of a vaccine has not been greeted with uniform enthusiasm, however. Although no credible evidence has been published to support their concern, some social conservatives in the U.S. fear that widespread (or mandatory) vaccination of adolescents will encourage sexual activity before marriage (Washington Post 2005 Oct 31, and Science 2005 Apr 29; 308:618). In the midst of this debate, at least one company is planning to seek FDA approval for their vaccine within months.
- Robert W. Rebar, MD
Published in Journal Watch Gastroenterology December 30, 2005
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