Administering Human Papillomavirus Vaccine (HPV) to both sexually active women and those who have never had sex could substantially reduce the incidence of HPV related cervical cancer and precancers, conclude authors of an Article published in this week's edition of the Lancet.
Cervical cancer is the second leading cause of death from cancer in women worldwide, and is caused by infection with oncogenic (cancer causing) types of human papillomavirus. Around 500,000 new cases are diagnosed each year, 80% in developing countries, resulting in 250,000 deaths.
Dr Kevin Ault, Emory University School of Medicine, Atlanta, Georgia, USA and colleagues from around the world formed the Future II Study Group to investigate the efficacy of the vaccine.
For women who have never had sex, the vaccine was 99% effective in stopping cervical cancer (adenocarcinoma in situ), and pre-cancerous lesions.
When data from women who could have been exposed was included, the vaccine efficacy was 44%.
The researchers enrolled over 20,000 women aged 15-26 from the Americas, Europe and Asia-Pacific in the study. Some 9,000 of these were given the full vaccine; around 1,200 were given a component of the vaccine and the rest a placebo.
The women involved were recruited at university student health centres, urban clinics, advertisements and by word of mouth. Healthy women who were not pregnant, had no report of a previous abnormal pap smear, and had a lifetime history of less than four to five sex partners were eligible.
The authors say that further follow-up of large trials will be needed to establish how long the vaccine remains effective.
They conclude: "The results of this quadrivalent HPV vaccine programme provide strong evidence that implementation of HPV vaccination campaigns in pre-adolescent girls and young adult women will reduce rates of cervical cancer worldwide."
In an accompanying comment, Dr Maurie Markman, University of Texas M.D. Anderson Cancer Centre, Houston, Texas, USA, says a number of questions remain around HPV vaccination, including how long the vaccine will work, the best age at which to administer it, its cost and whether men and boys should also be vaccinated.
He concludes: "Other important hurdles need to be overcome, including: the absence of health-delivery infrastructure in many countries to permit comprehensive vaccination programmes, the politically-charged debate surrounding the issue of voluntary versus mandatory vaccination, the existence of unsubstantiated claims that HPV vaccination will encourage promiscuity, and the belief by some that vaccination is unnecessary in the developed world due to the effectiveness of cervical cancer screening strategies."