The prognostic role of histomorphological subtyping in nonmetastatic papillary renal cell carcinoma after curative surgery: is subtype really irrelevant? A propensity score matching analysis of a multi-institutional real life data.

BACKGROUND AND AIM: The role of histomorphological subtyping is an issue of debate in papillary renal cell carcinoma (papRCC). This multi-institutional study investigated the prognostic role of histomorphological subtyping in patients undergoing curative surgery for nonmetastatic papRCC. PATIENTS AND METHODS: A total of 1,086 patients undergoing curative surgery were included from a retrospectively collected multi-institutional nonmetastatic papRCC database. The patients were divided into 2 groups based on histomorphological subtyping (type 1, n = 669 and type 2, n = 417). Furthermore, a propensity score-matching (PSM) cohort in 1:1 ratio (n = 317 for each subtype) was created to reduce the effect of potential confounding variables. The primary outcome of the study, the predictive role of histomorphological subtyping on the prognosis (recurrence free survival [RFS], cancer specific survival [CSS] and overall survival [OS]) in nonmetastatic papRCC after curative surgery, was investigated in both overall and PSM cohorts. RESULTS: In overall cohort, type 2 group were older (66 vs. 63 years, P = 0.015) and more frequently underwent radical nephrectomy (37.4% vs. 25.6%, P < 0.001) and lymphadenectomy (22.3% vs. 15.1%, P = 0.003). Tumor size (4.5 vs. 3.8 cm, P < 0.001) was greater, and nuclear grade (P < 0.001), pT stage (P < 0.001), pN stage (P < 0.001), VENUSS score (P < 0.001) and VENUSS high risk (P < 0.001) were significantly higher in type 2 group. 5-year RFS (89.6% vs. 74.2%, P < 0.001), CSS (93.9% vs. 84.2%, P < 0.001) and OS (88.5% vs. 78.5%, P < 0.001) were significantly lower in type 2 group. On multivariable analyses, type 2 was a significant predictor for RFS (HR:1.86 [95%CI:1.33-2.61], P < 0.001) and CSS (HR:1.91 [95%CI:1.20-3.04], P = 0.006), but not for OS (HR:1.27 [95%CI:0.92-1.76], P = 0.150). In PSM cohort balanced with age, gender, symptoms at diagnosis, pT and pN stages, tumor grade, surgical margin status, sarcomatoid features, rhabdoid features, and presence of necrosis, type 2 increased recurrence risk (HR:1.75 [95%CI: 1.16-2.65]; P = 0.008), but not cancer specific mortality (HR: 1.57 [95%CI: 0.91-2.68]; P = 0.102) and overall mortality (HR: 1.01 [95%CI: 0.68-1.48]; P = 0.981) CONCLUSIONS: This multiinstitutional study suggested that type 2 was associated with adverse histopathologic outcomes, and predictor of RFS and CSS after surgical treatment of nonmetastatic papRCC, in overall cohort. In propensity score-matching cohort, type 2 remained the predictor of RFS. Eventhough 5th WHO classification for renal tumors eliminated histomorphological subtyping, these findings suggest that subtyping is relevant from the point of prognostic view.

External validation of the VENUSS prognostic model to predict recurrence after surgery in non-metastatic papillary renal cell carcinoma: A multi-institutional analysis.

OBJECTIVE: Recently, VENUSS (VEnous extension, NUclear Grade, Size, Stage), as a prognostic model, was defined to predict disease recurrence (DR) after curative surgery of non-metastatic papillary renal cell carcinoma (papRCC). This study aimed to validate the VENUSS prognostic model in a large multi-institutional European cohort of patients with histopathologically proven papRCC after curative surgery for non-metastatic disease. PATIENTS AND METHODS: Overall, 980 patients undergoing partial or radical nephrectomy for sporadic, unilateral and non-metastatic papRCC between 1987 and 2020 were included from 7 European tertiary institutions. The primary outcome was the prediction of DR by VENUSS score and VENUSS risk groups. Chi-square, Kruskal-Wallis, Cox-regression and Kaplan-Meier survival analyses were used in statistical methods. The Concordance (C) Index was calculated to assess model's discriminatory power. RESULTS: The median age was 64 (IQR:55-70) years and 82.6 % (n = 809) of patients were male. Median VENUSS score was 2 (IQR: 0-4), and 62.9 % (n = 617), 23.9 % (n = 234) and 13.2 % (n = 129) of patients was classified into low, intermediate and high risk according to the VENUSS model, respectively. At a median follow-up of 48 (IQR:23-88) months, the disease recurred in 6.6%, 18.8% and 63.8%, and the 5-year recurrence-free survival was 93.8%, 80.7% and 26.7% in low, intermediate and high-risk groups, respectively. (P < 0.001) Each increase in VENUSS score had 1.52-fold (95%CI:1.45-1.60, P < 0.001) DR risk. Compared with the VENUSS low risk, the intermediate risk had a 2.91-fold increased DR risk (95%CI:1.90-4.46, P < 0.001) and 17.9-fold (95%CI:12.25-26.25, P < 0.001) in high risk, while it was 6.07-fold greater in high risk vs. intermediate risk (95%CI:4.17-8.83, P < 0.001). The discrimination was 81.2% (95%CI:77.5%-84.8%) for the VENUSS score, and 78.6% (95%CI:74.8%-82.4%) for VENUSS risk groups, respectively. Both the VENUSS score and groups were well calibrated. CONCLUSIONS: This contemporary multi-institutional European large dataset validated the use of VENUSS score and VENUSS risk groups on the prediction of DR after curative surgery in patients with non-metastatic papRCC. The VENUSS prognostic model can provide valuable information for patient counselling, follow-up and patient selection for adjuvant trials.