Mortality According to Treatment in Metastatic Collecting Duct Renal Cell Carcinoma

Introduction: Controlled contemporary analyses of mortality in metastatic collecting duct renal cell carcinoma (mcdRCC) are unavailable. We addressed this knowledge gap and tested rates of treatment and associated mortality in patients with mcdRCC. Patients and methods: Within Surveillance, Epidemiology, and End Results database (2004-2018), we identified 155 mcdRCC patients. Kaplan-Meier plots and Cox proportional hazards regression models tested the effect of treatment (cytoreductive nephrectomy [CN] alone vs. systemic therapy [ST] alone vs. combination of both CN + ST) on overall mortality (OM). Results: In the overall cohort (n = 155), 57 patients (37%) were treated with combination of both CN + ST, 46 (30%) underwent CN alone, 28 (18%) received ST alone, and 24 (15%) had none/unknown treatment. According to age categories (≤ 59 vs. 60-69 vs. ≥ 70 years), rates of combination of both CN + ST were 45% vs. 45% vs. 14%, respectively. CN alone was the most frequent type of treatment in patients aged ≥ 70 (50%). Median overall survival was 4.0 months for CN alone vs. 5.5 months for ST alone vs. 9.0 months for combination of both CN+ST. In multivariable Cox regression models, where CN alone was the referent, the use of ST alone and combination of both CN + ST were respectively associated with a HR of 0.74 (P = .3) and 0.43 (P < .001), after adjustment for all covariates. Conclusions: In mcdRCC patients, concomitant use of CN and ST results in lowest mortality, followed by ST alone, and CN alone. In consequence combination of both CN + ST should be recommended whenever applicable.