Racial Disparities in Survival Outcomes for Metastatic Renal Cell Carcinoma with Sarcomatoid Differentiation: A SEER-Based Retrospective Analysis (2010–2020)

Background: Sarcomatoid renal cell carcinoma (sRCC) is an aggressive RCC subtype with a poor prognosis. Although racial disparities in RCC outcomes are reported, survival patterns across racial and ethnic groups in metastatic sRCC (msRCC) remain unclear. Methods: We conducted a retrospective analysis of 2122 patients with msRCC diagnosed between 2010 and 2020 using the Surveillance, Epidemiology, and End Results (SEER) database. Patients were categorized by race and ethnicity as non-Hispanic White, non-Hispanic Black, Hispanic, Asian/Pacific Islander, or American Indian/Alaska Native. Three-year cancer-specific survival (CSS) and overall survival (OS) were estimated using Kaplan–Meier methods. Multivariable Cox proportional hazards regression models were used to evaluate racial disparities in survival. Results: Non-Hispanic Black patients experienced the poorest outcomes, with 3-year CSS and OS of 9.3% and 8.6%, compared with 23.3% and 20.9% in non-Hispanic White, 22.1% and 19.0% in Hispanic, 21.2% and 19.4% in Asian/Pacific Islander, and 23.4% and 20.7% in American Indian/Alaska Native patients. Non-Hispanic Black patients were associated with higher estimated hazards of cancer-specific mortality (HR = 1.5, p < 0.0001) and overall mortality (HR = 1.5, p < 0.0001) versus non-Hispanic White. From 2010–2015 to 2016–2020, survival improved across most racial groups with the introduction of immune checkpoint inhibitors. However, non-Hispanic Black patients remained the only group with persistently inferior survival. Subgroup analysis further demonstrated worse survival for non-Hispanic Black patients in both clear cell msRCC and non-clear cell msRCC subgroups. Conclusions: Although survival was higher during the later diagnosis period, non-Hispanic Black patients with msRCC continued to have the poorest observed survival. These differences may be associated with unmeasured social, structural, socioeconomic, healthcare access, treatment, or clinical factors, but their causes cannot be determined from this observational study. Further research is needed to identify the factors underlying these survival differences.