Nephron Sparing Surgery Has Better Oncologic Outcomes Than Extirpative Nephrectomy in T1a but Not in T1b or T2 Stage Renal Cell Carcinoma

Background: The aim of this study was to investigate the benefit of nephron sparing surgery (NSS) compared with extirpative nephrectomy in different tumor stages of renal cell carcinoma. Material/ Methods: We reviewed the Surveillance, Epidemiology and End Results (SEER) database for NSS and extirpative nephrectomy in localized (stages T1-2 N0M0) renal cell carcinoma diagnosed after 2004. We used the variable screening function of the SEER database to identified 55,947 cases that met inclusion and exclusion criteria for survival analysis. Overall mortality and cancer-specific mortality were the primary index outcomes. Stratification analysis was done by T stage subgroups. We also performed survival analysis using propensity score analysis, and changed the survival model to the competing-risk model for cancer-specific mortality analysis. Results: Overall, NSS significantly decreased the risk of overall mortality (HR 0.717, 0.668-0.769) and cancer-specific mortality (HR 0.604, 0.525-0.694) when compared to extirpative nephrectomy. In subgroup analysis, NSS had a lower overall mortality risk and cancer-specific mortality compared to extirpative nephrectomy only for T1a stage renal cell carcinoma (HR 0.654, 0.599-0.714, p<0.01 and HR 0.554, 0.458-0.670, p<0.01, respectively), but not for T1b or T2 stage. The propensity score analysis, which included standardized mortality ratio weight adjustment, showed the same results. Additionally, for cancer-specific mortality, a competing-risk model gave the exactly same outcome. Conclusions: Compared to extirpative nephrectomy, NSS provided superior overall survival and cancer-specific survival for localized renal cell carcinoma only in T1a stage, not in T1b or T2 stage. NSS should be recommended when the surgery is possible. Further prospective study is needed to confirm this result.