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

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.