Risk of cervical intraepithelial neoplasia grade 2 or worse after conization in relation to HPV vaccination status

Human papillomavirus (HPV) is essential for developing cervical cancer and precancerous lesions. Currently, three vaccines are available, which are effective as prophylaxis against HPV infection, however, limited knowledge exists about the possible effect of vaccinating women treated with conization to prevent recurrence. The aim of our study was to examine the risk of cervical intraepithelial neoplasia grade 2 or worse (CIN2+) after conization according to HPV vaccination status. Using Danish nationwide registries, we identified women diagnosed with CIN3 on the cone (2006-2012) and their HPV vaccination status. Vaccinees were defined as women vaccinated between 3 months before until 1 year after conization. The women were followed from 1 year after conization until diagnosis of CIN2+, conization, death, emigration or end of follow-up. Cox proportional hazard regression was used to estimate hazard ratios (HRs) and corresponding 95% confidence intervals (CIs) of CIN2+ comparing vaccinees with nonvaccinees. The HR was adjusted for age, histology on cone, education, year of conization, repeat conizations and CIN2+ lesions between conization and start of follow-up. Altogether 17,128 women were included (2,074 vaccinees). There was a statistically nonsignificant lower risk of CIN2+ among vaccinees (HR_adjusted = 0.86, 95% CI: 0.67-1.09). Women vaccinated 0-3 months before tended to have a slightly lower HR of CIN2+ (HR_adjusted = 0.77, 95% CI: 0.45-1.32) than women vaccinated 0-12 months after conization (HR_adjusted = 0.88, 95% CI: 0.67-1.14), although not statistically significantly different. Our results add to the current knowledge about the potential clinical effect of vaccination as an adjunct to conization of high-grade cervical neoplasia to decrease risk of recurrence.