Incidence of cervical precancerous lesions and cervical cancer in Denmark from 2000 to 2019: Population impact of multi‐cohort vaccination against human papillomavirus infection

In Denmark, vaccination against human papillomavirus (HPV) has been implemented in the children's vaccination program (January 2009) and in multiple catch‐up cohorts (October 2008 in girls 13‐15 years and in August 2012 in women up to 27 years). In the present study we estimate incidence of cervical intraepithelial neoplasia grade 3 (CIN3), adenocarcinoma in situ (AIS), squamous cell carcinoma (SCC) and adenocarcinoma (AC) during 2000‐2019. All cases of CIN3 and AIS were identified from the nationwide Pathology Data Bank, while SCC and AC were identified from the Danish Cancer Registry. We calculated age‐standardized incidence rates and estimated annual percentage change (EAPC) with corresponding 95% confidence interval (CI) for the periods before vaccination implementation (2000‐2005), early after implementation of childhood HPV vaccination and the first catch‐up vaccination program (2006‐2012), and after implementation of the second catch‐up program (2013‐2019). For CIN3 and AIS, age‐specific incidence rates and EAPCs were calculated. An increasing age‐standardized incidence was observed before introduction of HPV vaccination (2000‐2005) for CIN3 [EAPC(CIN3): 3.0 (95% CI 1.7 to 4.3)] and AIS [EAPC(AIS): 3.5 (95% CI 0.7 to 6.4)]. In the most recent period (2013‐2019), following implementation of the second catch‐up program, a decrease was observed for both CIN3 [EAPC(CIN3): ‐6.5 (95% CI ‐8.3 to −4.8)], AIS [EAPC(AIS): ‐8.7 (95% CI ‐12.3 to −5.1)] and for SCC [EAPC(SCC): ‐3.9 (95% CI ‐7.5 to −0.2)]. In this study we document a decrease in the incidence of CIN3, AIS and SCC in the period after implementation of multi‐cohort HPV vaccination in Denmark.