Trends in kidney cancer: exploring the impact of sex and age on stage of disease, and prognosis during the past three decades in Denmark-a DaRenCa study.

Renal cell carcinoma (RCC) management has advanced due to increased imaging-based diagnoses and improved therapies for metastatic disease. This nationwide registry-based cohort study examines changes in the number of primary RCC cases, stage at diagnosis, prognosis during the past 30 years in Denmark, and how these are associated with sex and age. All Danish patients aged 18 and older diagnosed with primary RCC from 1992 to 2021 with no prior cancer history (except non-melanoma skin cancer) were included and followed from diagnosis until death or end of follow-up (31-12-2023). Statistical analyses included Pearson's χ2, Cramer's V, Wilcoxon rank-sum test, Kruskal-Wallis, competing risk regression, Cox proportional hazard regression, and Kaplan-Meier. 17,423 RCC patients were identified. Primary RCC cases increased from 2,244 in 1992-1996 to 3,947 in 2017-2021. In this period, the proportion of male patients increased from 59 to 72% (P < 0.001). Male patients were younger at diagnosis than female patients (median age 65 vs. 69 years, P < 0.001). Localized cancer cases increased from 44% (N = 983) in 1992-1996 to 70% (N = 2,766) in 2017-2021, while metastatic cases declined from 29% (N = 640) to 17% (N = 652). Median survival for metastatic RCC improved from 4.1 months in 1992-1996 to 13.3 months in 2017-2021. Over three decades, RCC incidence in Denmark has grown, particularly among men, largely due to localized disease, adding pressure on urological departments. The number of metastatic cases remained stable, but survival improved, reflecting advances in early detection and treatment.