HPV Vaccine Achieves Population-Level Reduction of Cervical Cancer Lesions

March 3, 2014

In Denmark, researchers found that the risk of atypia, atypia+, and cervical intraepithelial neoplasia grade 2 or 3 (CIN2/3) were significantly reduced among women who received the vaccine.

The quadrivalent HPV vaccine is effective in reducing the risk of cervical lesions among Denmark girls, according to a study published in the Journal of the National Cancer Institute.

Pertinent Points

- The quadrivalent HPV vaccine reduced the risk of cervical lesions among Denmark women in the six years since the vaccine was approved in the country.

- The study assessed women born between 1989 and 1999, but found variations in the statistical significance of decrease in cervical lesions associated with the vaccine in different birth cohorts.

- The greatest risk reduction was found among the younger birth cohorts.

Six years after the vaccine became available in Denmark, the risk of atypia, atypia+, and cervical intraepithelial neoplasia grade 2 or 3 (CIN2/3) were statistically significantly reduced among women born between 1991 and 1994. Women born between 1989 and 1990 had a statistically significantly reduced risk of atypia+, but the risk of CIN2/3, while also decreased, was not statistically significantly reduced.

The study identified women born between 1989 and 1999 and used information on individual HPV vaccination status from 2006 to 2012. All information was obtained through national registries in Denmark. No cervical lesions were reported among women born between 1997 and 1999.

Among women who received at least one dose of vaccine, the risk for atypia or worse was statistically significantly reduced by up to 60% when compared with women who did not receive the vaccine. The risks for CIN2/3 and CIN3 were statistically significantly reduced by up to 80% for the same group when compared with nonvaccinated women, the authors reported. The greatest risk reduction was seen among the younger birth cohorts.

The authors pointed to a few limitations of the study, including that the national records did not provide information on HPV status, sexual history, or the HPV types responsible for cervical lesions later discovered. Still, the authors emphasized that the aim was to assess the ability to prevent disease overall and not to investigate specific types of lesions.

“The lower risk for cervical lesions among HPV-vaccinated women in our study is almost certainly due to a reduced risk for HPV16/18 lesions, although we had no information on the HPV types responsible for the cervical lesions detected,” wrote Susanne Krüger Kjaer, MD, DMSc, and her colleagues from the unit of Virus, Lifestyle and Genes, Danish Cancer Society Research Center in Copenhagen, Denmark.