MedPage Today (01.07.2014)
MedPage Today reported on a study of the quadrivalent human papillomavirus (HPV) vaccine effectiveness against cervical dysplasia. Salaheddin M. Mahmud, MD, PhD, of the University of Manitoba in Winnipeg, Canada, and colleagues reviewed records for 3,541 females who received HPV vaccines at age 15 and older in Manitoba from September 2006 to April 2010. The researchers matched each patient with three unvaccinated patients. The researchers calculated hazard ratios for atypical squamous cells of undetermined significance (ASCUS), low-grade squamous intraepithelial lesions (LSIL), and high-grade squamous intraepithelial lesions (HSIL).
A median follow-up of 3.1 years showed vaccinated patients’ LSIL and HSIL rates were 3.3 percent and 2.3 percent, respectively, compared with 3.7 percent and 2.6 percent for unvaccinated individuals. None of the patients developed cervical cancer during follow-up, but 12 vaccinated and 22 unvaccinated patients had carcinoma in situ.
The researchers analyzed data by age group and history of abnormal cervical cytology. Results showed that women ages 18 and older or who had abnormal cervical cytology at the time of HPV vaccination had rates of cervical dysplasia similar to those of unvaccinated women. Women ages 18 and older without cervical abnormalities when vaccinated had a 23-percent reduction in risk of HSIL compared with unvaccinated women. The vaccine did not seem to protect women from HSIL who had abnormal cytology when they were vaccinated.
Mahmud concluded that the vaccine may not protect some women from HSIL or lesser dysplasia if they were vaccinated at an older age or had abnormal cytology prior to vaccination. The researchers concluded that findings confirmed the importance of vaccination before significant exposure to HPV and emphasized the need to screen all sexually active women even if they had been vaccinated.
The full report, “Effectiveness of the Quadrivalent Human Papillomavirus Vaccine Against Cervical Dysplasia in Manitoba, Canada,” was published online in the Journal of Clinical Oncology (2014; doi:10.1200/JCO.2013.52.4645).