HPV Genotype Distribution in Cervical Cancer and High-Grade Lesions in Norway, and Early Vaccine Impact.

Abstract

All cases of invasive cervical cancer (ICC) and subsets of high-grade cervical intraepithelial neoplasia grade 2 or 3 (CIN2/3) and adenocarcinoma in situ (AIS) in Norway are tested for 37 human papillomavirus (HPV) genotypes, within a mandatory national surveillance system. We assessed the proportional attribution of HPV types in cervical lesions from predominantly unvaccinated women reported during 2017-2021 (baseline population) and the HPV type distribution by vaccination status in vaccine-eligible cases reported during 2017-2024. Among baseline CIN2/3 cases (n = 3087), 48% were attributable to HPV16/18, 28% to HPV31/33/45, 12% to HPV52/58 and 8% to other high-risk types (HPV35/39/51/56/59). For AIS (n = 550), almost all cases were attributed to HPV16/18 (91%) and HPV45 (6%). For ICC (n = 1265), 75% were attributable to HPV16/18, 15% to HPV31/33/45, 3% to HPV52/58 and 4% to other high-risk types. Among CIN2/3 cases born 1997 or later (eligible for vaccination at age 11-12 years, n = 154), HPV16-attribution was higher in unvaccinated cases (49.9%, 95% CI: 33.7-66.1) than in cases vaccinated before age 15 (1.1%, 95% CI: 0-3.4). In CIN2/3 cases born 1991-1996 (eligible for catch-up vaccination, n = 1541), HPV16-attribution was 45.7% (95% CI: 41.9-49.7) in unvaccinated versus 35.5% (95% CI: 32.5-38.6) in vaccinated cases. Minor differences by vaccination status were observed for catch-up-eligible AIS (n = 445) and ICC (n = 135) cases. In conclusion, the baseline genotype distribution in high-grade cervical lesions and ICC in Norway aligns with global data. Strong protection against HPV16-induced CIN2/3 was seen in women vaccinated before age 15 years.