Low-Grade Cervical Intraepithelial Neoplasia (CIN1) Evolution: Analysis of Opportunistic Preventive Vaccination Role

Low-grade cervical lesions have a high percentage of clearance in young women, even if 71-82% of low-grade intraepithelial lesion/atypical squamous cells of undetermined significance (LSIL/ASCUS) reported a High-Risk Human Papillomavirus (HR-HPV) infection, which correlates with an increased risk of Cervical Intraepithelial Neoplasia (CIN)2+. The immunogenic effect of the anti-HPV vaccine appears to be significant. The aim of the study is to evaluate the effect, two years after the diagnosis, of the anti-HPV preventive vaccination on patients with low-grade cervical lesions.

We collected clinical, colposcopic, histological, and virological data from patients aged 21-45 years who attended the colposcopy service of the department of Obsetrics and Gynecology of IRCCS Foundation Policlinico San Matteo, Pavia, Italy. In the 2005-2019 period and had a low-grade pap-smear.

We enrolled 422 women consecutively, divided into two groups (vaccinated and not vaccinated) for the retrospective analysis. The rate of persistence and progression of CIN were higher in the not-vaccinated group (p = 0.019). The relative risk (RR) to develop CIN2+ during follow-up vs. the the CIN1 persistence was 1.005 (95% Confidence Interval-CI 0.961-1.051) vs. 0.994 (95% CI 0.994-1.018) for age, 3.472 (95% CI 1.066-11.320) vs. 1.266 (95% CI 0.774-2.068) for non-vaccinated, 0.299 (95% CI 0.088-1.018) vs. 0.518 (95% CI 0.242-1.109) for HIV status negative, respectively. Analyzing the time to negativity, the odds ratio (OR) was 1.012 (95% CI 1-1.024) for age and 1.591 (95% CI 1.223-2.069) for vaccination; on the other hand, considering the relationship between the time to negative and the HPV genotypes contained in the 9-valent HPV vaccines, the OR was 1.299 (95% CI 1.026-1.646) for at least one of these at recruitment and 0.631 (95% CI 0.471-0.846) at follow-up. Furthermore, the presence of at least one of the HPV genotypes targeted by the HPV nonavalent vaccine is a key indicator of the risk of progression to CIN2+: OR was 3.443 (95% CI 1.065-11.189) for the presence of at least one HPV genotype at enrollment and 5.011 (95% CI 1.899-13.224) for the presence of at least one HPV genotype at follow-up, respectively.

We reported in a retrospective study the benefit of anti-HPV vaccination in promoting negativity and increasing low-grade cervical lesions regression.