The risk of cervical cancer after cervical intraepithelial neoplasia grade 3: A population-based cohort study with 80,442 women.

To estimate the risk of cervical cancer in women with a history of cervical intraepithelial neoplasia (CIN) grade 3 and to review the compliance with post-treatment follow-up.A population-based retrospective cohort study including 80,442 women with a median follow-up of 15.8 years, and 1,278,297 person years. Women with CIN3 between 1990 and 2010 were identified from the Dutch Pathology Registry (PALGA) and linked to the general female population from the Netherlands Cancer Registry. Cases of recurrent CIN3 and cervical cancer, defined as occurrence minimally two years post-treatment, were identified until 2016. Standardized incidence ratios (SIRs) were calculated for the risk of cervical cancer.1554 women (1.9%) developed recurrent CIN3 and 397 women (0.5%) cervical cancer. Women with CIN3 were associated with a twofold increased risk of cervical cancer (SIR 2.29; 95%CI 2.07-2.52) compared with the general female population. Women aged ≥50 years during CIN3 diagnosis had a sevenfold and women with recurrent CIN3 a ninefold increased risk of developing cervical cancer. The increased risk up to 20 years of follow-up seems to be mostly attributable to ageing. 37.0% of women who developed cervical cancer after CIN3 did not complete the advised post-treatment follow-up.Women with CIN3 have a long-lasting twofold increased risk of developing cervical cancer, even when they complete the post-treatment follow-up and adhere to the regular screening program. This risk increases with CIN3 diagnosis at older age, further ageing during follow-up and in women with recurrent CIN3. Studies on optimizing follow-up strategies are warranted.