Prognostic Factors for Renal Cell Carcinoma Subtypes Diagnosed According to the 2016 WHO Renal Tumor Classification: a Study Involving 928 Patients

The morphotype and grade of renal cell carcinoma (RCC) in 928 nephrectomies were reclassified according to the 2016 WHO classification in order to analyze the distribution and outcomes of RCC subtypes in Hungary, to assess whether microscopic tumor necrosis is an independent prognostic factor in clear cell RCC, and to study whether a two-tiered grading (low/high) for clear cell and papillary RCC provides similar prognostic information to that of the four-tiered ISUP grading system. 83.4% of the cohort were clear cell, 6.9% papillary, 4.5% chromophobe, 2.3% unclassified, 1.1% Xp11 translocation, 1.1% clear cell papillary, 0.3% collecting duct and 0.1% mucinous tubular and spindle cell RCCs. RCC occurred in 16 patients with end-stage kidney disease and none of them displayed features of acquired cystic kidney disease-associated RCC. The 5-year survival rates were as follows: chromophobe 100%, clear cell papillary 100%, clear cell low-grade 96%, papillary type 1 92%, clear cell high-grade 63%, papillary type 2 65%, unclassified 46%, Xp11 translocation 20%, and collecting duct 0%. The 5-year survival rates in low-grade and high-grade papillary RCC were 95% and 59%, respectively. In clear cell RCC, only the grade, the stage and the positive surgical margin proved to be independent prognostic factors statistically. Overall, papillary RCC occurred relatively infrequently; microscopic tumor necrosis in clear cell RCC did not predict the outcome independently of the tumor grading; and the assignment of clear cell and papillary RCCs into low-grade or high-grade tumors was in terms of survival no worse than the ISUP grading.