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A randomised trial in this week's issue of THE LANCET shows how a vaccine against human papillomavirus (HPV) infection could potentially reduce the global incidence of cervical cancer.
Nearly a quarter of a million women die every year from cervical cancer worldwide, and epidemiological studies over the past two decades have confirmed the cause--certain types of HPV infection. Vaccination against the most common cancer-causing HPV types, HPV-16 and HPV-18, could prevent the development of up to 70% of cervical cancers.
Diane M Harper (Norris Cotton Cancer Center and Dartmouth Medical School, USA) and colleagues did a randomised controlled trial to assess the efficacy of a vaccine containing HPV 16 and 18 in the prevention of incident and persistent HPV infection, associated cervical abnormalities, and precancerous lesions. 1113 women aged 15–25 years from North America and Brazil received three doses of either the vaccine or placebo.
In those women who completed the protocol (721 or 65% of those originally enrolled), the vaccine was effective against 100% of the persistent HPV 16/18 infections. Among the 1113 women in the study, when considering any woman who received at least one dose of vaccine, the efficacy was 95% against persistent HPV 16/18 infection, 93% against abnormal Pap tests associated with HPV 16/18 infections, and completely protected against cervical tissue pre-cancers associated with HPV 16/18.
Dr Harper comments: "Our findings indicate that the vaccine could contribute substantially to reducing worldwide rates of cervical cancer. However, large-scale trials with long-term follow-up are needed to extend our findings and confirm that vaccination prevents cervical cancer."
In an accompanying commentary (p 1731), Matti Lehtinen and Jorma Paavonen (University of Helsinki, Finland) state: "Licensure of the HPV vaccine is not far away. It will probably be the first licensed vaccine against a common sexually transmitted infection. However, the implementation should be accomplished in a controlled way with community randomised trials. Several questions on the effectiveness and the public-health impact of vaccine implementation remain unanswered. How to implement HPV vaccination in national vaccination programmes to guarantee high coverage in adolescents before they become sexually active? Should both girls and boys be vaccinated? How many oncogenic HPV types should the vaccine contain? Is resurgence of oncogenic HPV types not included in the vaccine a real threat? When is booster vaccination required? They conclude: "While we trust that the remaining questions can be answered, a straightforward message of Harper and colleagues' work is that preventive vaccination against the oncogenic HPV types will soon be available."
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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