Prognostic effect of preoperative serum albumin to globulin ratio in patients treated with cytoreductive nephrectomy for metastatic renal cell carcinoma

Background: Accurate identification of ideal candidates for cytoreductive nephrectomy (CN) for metastatic renal cell carcinoma (mRCC) is an unmet need. We tested the association between preoperative value of systemic albumin to globulin ratio (AGR) and overall survival (OS) as well as cancer-specific survival (CSS) in mRCC patients treated with CN. Methods: mRCC patients treated with CN were included. The overall population was therefore divided into two AGR groups using cut-off of 1.43 (low, <1.43 vs. high, >= 1.43). Univariable and multivariable Cox regression analyses tested the association between AGR and OS as well as CSS. The discrimination of the model was evaluated with the Harrel's concordance index (C-index). The clinical value of the AGR was evaluated with decision curve analysis (DCA). Results: Among 613 mRCC patients, 159 (26%) patients had an AGR <1.43. Median follow-up was 31 (IQR: 16-58) months. On univariable analysis, low preoperative serum AGR was significantly associated with both OS (HR: 1.55, 95% CI: 1.26-1.89, P<0.001) and CSS (HR: 1.55, 95% CI: 1.27-1.90, P<0.001). On multivariable analysis, AGR <1.43 was associated with worse OS (HR: 1.51, 95% CI: 1.23-1.85, P<0.001) and CSS (HR: 1.52, 95% CI: 1.24-1.86, P<0.001). The addition of AGR only minimally improved the discrimination of a base model that included established clinicopathologic features (C-index=0.640 vs. C-index=0.629). On DCA, the inclusion of AGR marginally improved the net benefit of the prognostic model. Low AGR remained independently associated with OS and CSS in the IMDC intermediate risk group (HR: 1.52, 95% CI: 1.16-1.99, P=0.002). Conclusions: In our study, low AGR before CN was associated with worse OS and CSS, particularly in intermediate risk patients.