Long-Term Regional Pathology-Detection Trends in High-Grade Cervical Lesions and Cervical Squamous Cell Carcinoma Among Women Aged 40-69 Years in Northern Norway, 1998-2025.

Background/Objectives: Norway has transitioned from cytology-based to HPV-based cervical screening. We examined long-term trends in histologically confirmed cervical intraepithelial neoplasia grade 2 or worse (CIN2+), grade 3 or worse (CIN3+), and cervical squamous cell carcinoma (SCC) among women aged 40-69 years in Troms and Finnmark, a population largely ineligible for programme-based HPV vaccination. Methods: This retrospective, regional repeated cross-sectional study used routine pathology records from the University Hospital of North Norway from 1998 to 2025. Cervical samples obtained through primary screening, follow-up, and clinical indications were included. The most severe histological diagnosis per woman and calendar year was retained. Annual detection rates were calculated per 1000 women with at least one registered cervical sample. Temporal trends were assessed using negative binomial regression with annual endpoint counts as outcomes and the annual cervical-sampling denominator as an offset. All SCC diagnoses were included irrespective of symptoms or mode of detection. Results: The study comprised 350,868 annual woman-records, 3049 CIN2+, 1596 CIN3+, and 143 SCC diagnoses. CIN2+ detection increased significantly over time (rate ratio [RR] per calendar year, 1.025; 95% confidence interval [CI], 1.016-1.035; p < 0.001), whereas CIN3+ detection decreased (RR, 0.987; 95% CI, 0.980-0.995; p = 0.002). No significant temporal trend was observed for SCC (RR, 0.995; 95% CI, 0.971-1.020; p = 0.704). Conclusions: CIN2+ detection increased, CIN3+ detection decreased, and SCC showed no significant temporal trend during substantial changes in screening and diagnostic practice. The independent contributions of screening modality, screening intervals, diagnostic activity, histopathological practice, local HPV mRNA-based quality assurance, and denominator changes cannot be separated. The reported rates represent regional pathology detection relative to cervical-sampling activity rather than population incidence.