Estimating the direct effect of human papillomavirus vaccination on the lifetime risk of screen-detected cervical precancer.

Abstract

Birth cohorts vaccinated against human papillomavirus (HPV) are now entering cervical cancer screening. Assessment of (pre)cancer (CIN3+) risk is needed to assess the residual screening need in vaccinated women. We estimated the lifetime (screen‐detected) CIN3+ risk under five‐yearly primary HPV screening between age 30 and 60, using HPV genotyping and histology data of 21,287 women participating in a screening trial with two HPV‐based screening rounds, 5 years apart. The maximum follow‐up after an HPV‐positive test was 9 years. We re‐estimated the CIN3+ risk after projecting direct vaccine efficacy for the bivalent and the nonavalent HPV vaccines, assuming life‐long protection. The lifetime CIN3+ risk was 4.1% (95% confidence interval 3.5‐4.9) and declined by 53.5% and 70.5% after bivalent vaccination without and with cross‐protection, respectively, translating into a residual lifetime CIN3+ risk of 1.9% (1.4‐2.4) and 1.2% (0.9‐1.5). The CIN3+ risk declined by 88.5% after nonavalent vaccination, translating into a residual lifetime CIN3+ risk of 0.5% (0.2‐0.7). The latter risk increased to 1.6% when vaccine protection only lasted until the first screening round at age 30. Among HPV‐positive women with abnormal adjunct cytology, the nine‐year CIN3+ risk was 16.9% (8.7‐32.4) after nonavalent vaccination. In conclusion, HPV vaccination will lead to a strong decline in the lifetime CIN3+ risk and the remaining absolute CIN3+ risk will be very low. Primary HPV testing combined with adjunct cytology at five‐year intervals still seems feasible even after nonavalent vaccination, although unlikely to be cost‐effective. Our results support a de‐intensification of screening programs in settings with high vaccination coverage.