External validation of the REMARCC model for the selection of cytoreductive nephrectomy in patients with primary metastatic renal cell carcinoma: A multicenter retrospective study.

Objectives This study aims to evaluate the utility of the scoring system of the Registry for Metastatic Renal Cell Carcinoma (REMARCC) model on the overall survival (OS) of patients undergoing cytoreductive nephrectomy (CN). Methods A total of 278 patients with primary metastatic renal cell carcinoma (mRCC) treated with first-line tyrosine kinase inhibitors (TKIs) between January 2008 and November 2019 were identified. The c-index and net benefit between the REMARCC score were compared with the International mRCC Database Consortium (IMDC) score in patients with CN (CN group, n = 146). The effect of the REMARCC score on OS was compared between the CN group and patients without CN (non-CN group, n = 132) using Cox regression analysis under the propensity score-based inverse probability of treatment weighting (IPTW) method to adjust for group imbalances. Results Of the 146 patients with CN, the c-index of the REMARCC model (0.60) was higher than the IMDC model (0.54). The decision curve analysis showed the advantage of REMARCC model predicting OS compared with the IMDC model. OS was significantly longer in the REMARCC low-score (0-2) than that in the high-score (3-6) among the patients with CN. IPTW-adjusted Cox regression analyses showed that OS was significantly longer in the CN group than that in the non-CN group among the patients with REMARCC low-score but was not significantly different between the groups among the patients with REMARCC high-score. Conclusions The REMARCC score may be active for selecting the CN candidate in patients treated with TKIs.