Cytoreductive nephrectomy for patients with metastatic non-clear cell renal cell carcinoma: Results from a matched 15-year retrospective cohort.

e16537 Background: Upfront cytoreductive nephrectomy (CN) was not associated with improved outcomes in patients (pts) with intermediate or poor-risk clear cell renal cell carcinoma (RCC), although CN may still benefit a subset of pts. We aimed to evaluate the impact of CN in pts with metastatic non-clear cell RCC (nccRCC). Methods: We reviewed our institutional database (São Paulo State Cancer Institute, University of São Paulo) to identify pts with metastatic nccRCC. Electronic medical records were reviewed to register clinical and pathological features. Histological subtypes were classified as per the 2022 World Health Organization classification. CN was considered as any nephrectomy performed in the setting of metastatic disease. Survival probabilities were estimated using the Kaplan-Meier method and compared via the log-rank test. To adjust for imbalances between CN recipients and non-recipients, propensity score matching was applied based on the International Metastatic RCC Database Consortium (IMDC) classification, ECOG-PS, histologic subtype and number of affected organs. Results: From September 2009 to January 2024, we identified 2,867 pts with kidney cancer. Among 620 pts diagnosed with nccRCC, 146 (23.5%) had metastatic disease, and CN was performed in 28 pts. Clinicopathological features of pts treated with CN vs. non-treated with CN are described in the table. CN was not associated with improved overall survival (OS) after propensity score matching (median OS 18.9 vs. 15.0 months, HR 0.81, 95% CI 0.45-1.45). In the matched cohorts, CN was associated with improved OS in the poor IMDC cohort (median OS 18.9 vs 4.5 month, HR 0.29, 95% CI 0.08-0.98), but not in the papillary subtype (median OS 21.9 vs 19.6 months, HR 0.9, 95% CI 0.39-2.06) and intermediate IMDC risk pts (median OS 12.2 vs 19.6 months, HR 1.08, 95% CI 0.49-2.43). Conclusions: This retrospective analysis suggests that CN may associate with improved OS in pts with nccRCC and poor IMDC-risk classification. Our findings should be validated in prospective studies, given selection bias may affect the interpretation of these results. Clinicopathological features of pts treated with CN vs. non-treated with CN. Variable CN (%)28 pts Non-CN (%)118 pts Age in years (mean) 52.39 55.24 T StageT1- T2T3-T4 3 (11)22 (79) 22 (19)68 (58) IMDCFavorableIntermediatePoor 2 (7)15 (54)9 (32) 27 (23)49 (41)40 (34) ECOG0 – 1≥2 20 (71)7 (25) 73 (62)35 (30) SubtypePapillary Chromophobe MiT Translocation Unclassified Others 13 (46)3 (11)3 (11)5 (18)4 (14) 59 (50)17 (14)9 (8)20 (17)13 (11) MetastasisLungLiverCentral nervous systemBone 17 (61)7 (25)3 (11)11 (39) 59 (50)41 (35)12 (10)48 (41) Systemic treatmentSunitinib PazopanibChemotherapy 5 (18)8 (29)4 (14) 11 (9)45 (38)4 (10) Best responsePartial responseStable diseaseProgressive diseaseUnknown 6 (21)2 (7)7 (25)2 (7) 16 (14)13 (11)33 (26)10 (8)