HPV types 16 and 18 account for 70% or more cases of cervical cancer worldwide, but there are up to 15 oncogenic HPV types which can contribute to cervical cancer.
Professor Jorma Paavonen, Department of Obstetrics and Gynaecology, University of Helsinki, Finland, and colleagues randomly assigned 9 258 women to receive the HPV 16/18 vaccine, and 9 267 women in a control group received Hepatitis A vaccine. Women who may have already been infected with HPV were included in the study, as were women who had low-grade cytological abnormalities at study entry.
With an average follow-up of 15 months, the investigators found the vaccine had 90·4% efficacy against high-grade cervical intraepithelial neoplasia (CIN 2/3, a cervical cancer precursor) associated with HPV types 16 and 18. They found also that many CIN lesions contained several oncogenic HPV types. The level of protection against persistent infections with HPV16/18 at 6 and 12 months was 80·4% and 75·9%, respectively. The study extended earlier results of cross-protection against HPV 45 and HPV 31, which cause up to 10% of cases of cervical cancer.
The authors say: "Our results show that the vaccine is effective, well-tolerated and immunogenic in a broad population of young adult women, lending support to its potential value in preventing CIN and cervical cancer."
In an accompanying Comment, Dr Jessica Kahn, Cincinnati Children’s Medical Center, University of Cincinnati College of Medicine, USA, and Dr Robert Burk, Albert Einstein College of Medicine, New York, USA, state: "Althou gh these interim efficacy data are encouraging, their interpretation has limitations. The follow-up was brief, given that cervical carcinogenesis often evolves over several decades. They also highlight increases in adverse reactions among women in the HPV vaccine group.
Finally, the Comment authors raise the issue of ensuring the vaccine is distributed in the developing world, where cervical cancer makes the largest contribution to years of life lost to cancer, concluding: "Poverty is strongly associated with high-risk HPV infection and cervical cancer. If those who live in poverty cannot access a highly effective intervention such as HPV vaccines, disparities could worsen dramatically."
Professor Jorma Paavonen, Department of Obstetrics and Gynaecology, University of Helsinki, Finland. T) +35 8400497900
Comment Dr Jessica Kahn, Cincinnati Children’s Medical Center, University of Cincinnati College of Medicine, USA. T) +1 513 636 8587