Reassessment of American Joint Committee on Cancer Staging for Stage III Renal Cell Carcinoma With Nodal Involvement: Propensity Score Matched Analyses of a Large Population-Based Study

Background: To assess the role of nodal involvement in stage III renal cell carcinoma (RCC) according to the American Joint Committee on Cancer (AJCC) 8th staging system. We compared the survival outcomes of RCC patients with pT(1−3)N(1)M(0) disease and those with pT(3)N(0)M(0) or stage IV (stratified as pT(4)N(any)M(0) and pT(any)N(any)M(1)) disease in a large population-based cohort. Methods: A cohort of 3,112 eligible patients with RCC was identified from the Surveillance, Epidemiology, and End Results (SEER) database, registered between January 2004 and December 2015. Kaplan-Meier and Cox proportional hazards models were used to evaluate the overall survival (OS), and cancer-specific survival (CSS). The prognostic value of the modified stage for pT(1−3)N(1)M(0) disease was assessed by nomogram-based analyses. Propensity score matching (PSM) was used to adjust for potential baseline confounding. Results: Patients with pT(1−3)N(1)M(0) disease showed similar survival outcomes (median OS 41.0 vs. 38.0 months, P = 0.77; CSS 45.0 vs. 39.0 months, P = 0.59) to pT(4)N(any)M(0) patients, whereas the significantly better survival outcome was found for pT(3)N(0)M(0) patients. After PSM, comparable survival rates were observed between pT(1−3)N(1)M(0) group and pT(4)N(any)M(0) group, which were still significantly worse than the survival of pT(3)N(0)M(0) patients. The modified stage IIIA (pT(3)N(0)M(0)), IIIB (pT(1−3)N(1)M(0), pT(4)N(any)M(0)), and IV (pT(any)N(any)M(1)) showed higher predictive accuracy than AJCC stage system in the nomogram-based analyses (concordance index: 0.70 vs. 0.68, P < 0.001 for OS; 0.71 vs. 0.69, P < 0.001 for CSS). Conclusions: The pT(1−3)N(1)M(0) RCC might be reclassified as stage IIIB together with pT(4)N(any)M(0) disease for better prediction of prognosis, further examination and validation are warranted.