An epidemiological and clinicopathological study of type 1 vs. type 2 morphological subtypes of papillary renal cell carcinoma– results from a nation-wide study covering 50 years in Iceland

• Published in: BMC Urology
• Main Authors: Thorri Geir Runarsson, Andreas Bergmann, Gigja Erlingsdottir, Vigdis Petursdottir, Leon Arnar Heitmann, Aevar Johannesson, Viktor Asbjornsson, Tomas Axelsson, Rafn Hilmarsson, Tomas Gudbjartsson
• Format: Article in Journal/Newspaper
• Language: English
• Published: BMC 2024
• Subjects: Papillary renal cell carcinoma; Renal cell carcinoma; Histology; Subtyping; Kidney cancer; Renal cancer; Diseases of the genitourinary system. Urology; RC870-923; Iceland
• Online Access: https://doi.org/10.1186/s12894-024-01494-9; https://doaj.org/article/d63c25f2fa0f4684b3ba65f8cea34926

Abstract Introduction Papillary renal cell carcinoma (pRCC) is the second most common histology of renal cell carcinoma (RCC), accounting for 10–15% of cases. Traditionally, pRCC is divided into type 1 and type 2, although this division is currently debated as a prognostic factor of survival. Our aim was to investigate the epidemiology and survival of the pRCC subtypes in a whole nation cohort of patients during a 50-year period. Materials and methods A Population based retrospective study including consecutive cases of RCC in Iceland from 1971–2020. Comparisons were made between histological classifications of RCC, with emphasis on pRCC subtypes (type 1 vs. 2) for outcome estimation. Changes in RCC incidence were analyzed in 5-year intervals after age standardization. The Kaplan–Meier method and Cox regression were used for outcome analysis. Results A total of 1.725 cases were identified, with 74.4%, 2.1% and 9.2% having clear cell (ccRCC), chromophobe (chRCC), and pRCC, respectively. The age standardized incidence (ASI) of pRCC was 1.97/100.000 for males and 0.5/100.000 for females, and the proportion of pRCC increased from 3.7% to 11.5% between the first and last intervals of the study (p < 0.001). Age standardized cancer specific mortality (ASCSM) of pRCC was 0.6/100.000 and 0.19/100.000 for males and females, respectively. The annual average increase in ASI was 3.6% for type 1 pRCC, but the ASI for type 2 pRCC and ASCSM for both subtypes did not change significantly. Male to female ratio was 4.4 for type 1 pRCC and 2.3 for type 2. The average tumor size for type 1 and 2 was 58.8 and 73.7 mm, respectively. Metastasis at diagnosis was found in 8.7% in the type 1 pRCC, compared to 30.0% of patients with type 2 pRCC (p < 0.001). Estimated 5-year cancer-specific survival (CSS) were 94.4%, 80.7%, and 69.3% for chRCC, pRCC and ccRCC, respectively (p < 0.001). For the pRCC subtypes, type 1 was associated with better 5-year CSS than type 2 (86.3% vs. 66.0%, p < 0.001), although this difference was not ...