Role of cytoreductive nephrectomy in metastatic medullary renal cell carcinoma: controlled analysis

To test for differences in overall survival (OS) according to cytoreductive nephrectomy (CN) in medullary metastatic renal cell carcinoma (med-mRCC) relative to most comparable clear cell metastatic RCC (cc-mRCC) patients.

Within the Surveillance, Epidemiology and End Results (SEER) database (2000-2021), we identified 62 patients with med-mRCC vs. 10,372 with cc-mRCC. Propensity score matching (PSM, ratio 1:3), Kaplan-Meier plots and multivariable Cox regression analyses addressed were used.

Of 10,434 patients, 62 (0.6%) harbored med-mRCC vs. 10,372 (99.4%) cc-mRCC. Med-mRCC patients were younger (27 vs. 63 years, p < 0.001), more frequently African American (74 vs. 6%, p < 0.001) and more frequently harbored N1 stages (52 vs. 28%, p < 0.001). After 1:3 PSM for age, race/ethnicity, T-stage and N-stage, 62 of 62 (100%) med-mRCC (median OS 4 months) and 186 of 10,372 (2%) cc-mRCC patients (median OS 10 months) remained for further analyses. In med-mRCC, median OS was 9 months with CN vs. 3 months without CN (p = 0.01). In cc-mRCC, median OS was 28 months with CN vs. 5 months without CN (p < 0.001). In med-mRCC, CN independently predicted better OS (Hazard's Ratio [HR] 0.5, p = 0.005), as well as in cc-mRCC (HR 0.4, p < 0.001).

Med-mRCC patients exhibit a drastically different phenotype relative to their cc-mRCC counterparts. Despite this difference, med-mRCC exposed to CN harbor a similar relative protective survival effect compared to their cc-mRCC counterparts with most comparable age, race/ethnicity and tumor characteristics.