Prevalence and Risk Factors of Human Papillomavirus Infection in 18-Year-Old Women: Baseline Report of a Prospective Study on Human Papillomavirus Vaccine.

Abstract

Little is known about the epidemiology of human papillomavirus (HPV) in Italy before the age of 25. At the European Institute of Oncology, a prospective observational study on cervical HPV infection in 18-year-old women undergoing quadrivalent HPV vaccination is ongoing. At the first visit before vaccination, all the young women answered an epidemiological questionnaire, and then, the presence of high-risk HPV (hrHPV) was tested. Samples positive for hrHPV were genotyped. Liquid-based cytology was done only to women declaring not to be virgins. Any positivity at cytology or HPV testing was completed with colposcopy and eventually biopsies. Seven hundred and thirty women were enrolled. Two hundred sixty-six women were virgins; 7 (2.6%) of these resulted positive to hrHPV: 1 had HPV16 and CP6108, whereas the other 6 resulted negative at genotyping. Of the 464 nonvirgins, 61 (13.1%) were HPV positive: 19 had HPV16, 4 were positive to HPV18 with other hrHPVs, 25 to other hrHPVs, 7 to low-risk HPV, whereas 13 resulted negative at genotyping. HPV positivity was significantly associated to both smoking and having more than 3 partners. Cervical cytology was negative in 433 cases (93.3%), ASC-US in 10 cases (2.2%), low-grade squamous intraepithelial lesion in 20 cases (4.3%), and ASC-H in 1 case (0.2%). No CIN2+ was identified. Overall, we found a low positivity to HPV in this population; however, the rate of HPV positivity was significantly related to smoking and sexual life. The cytology result low-grade squamous intraepithelial lesion was more frequent than in the screening population, whereas no CIN2+ was identified, confirming the indication to avoid screening at this age.