The Royal Marsden Hospital Score Independently Predicts Overall Survival in Patients with De Novo Metastatic Renal Cell Carcinoma Treated with First-Line Tyrosine Kinase Inhibitors: A Multicenter Retrospective Analysis

Background: Accurate prognostic stratification is essential for clinical decision-making in metastatic renal cell carcinoma (mRCC). Although the International Metastatic RCC Database Consortium (IMDC) model is widely used, its discriminatory capacity may be limited in specific clinical subpopulations. The Royal Marsden Hospital (RMH) score, based on serum albumin, lactate dehydrogenase, and the number of metastatic sites, has not been evaluated as a prognostic tool in patients with de novo mRCC receiving first-line tyrosine kinase inhibitor (TKI) therapy. Methods: We retrospectively analyzed the data of 149 patients with de novo metastatic renal cell carcinoma who received first-line TKI therapy (pazopanib, sunitinib, or cabozantinib) at two tertiary oncology centers in Turkey. Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan–Meier method. Univariate and multivariate Cox proportional hazards regression analyses were performed to identify independent prognostic factors. Results: The median OS and PFS were 23.1 months (95% CI: 19.4–26.8) and 9.4 months (95% CI: 7.0–11.8), respectively. The OS showed a stepwise decline across RMH risk groups, ranging from 40.7 months in patients with an RMH score of 0 to 8.6 months in those with an RMH score of 3. In the multivariate analysis, the RMH score (HR 1.29, 95% CI: 1.03–1.61; p = 0.026) and sarcomatoid differentiation (HR 2.01, 95% CI: 1.09–3.72; p = 0.025) were independently associated with worse OS. The IMDC score did not retain independent prognostic significance (p = 0.129). The RMH score was not significantly associated with PFS after multivariable adjustment, and the IMDC score was not significantly associated with PFS in univariate analysis and was therefore not entered into the multivariable PFS model. Conclusions: The RMH score independently predicted overall survival in patients with de novo mRCC receiving first-line TKI therapy, whereas the IMDC score did not retain independent prognostic significance in this cohort. Given its simplicity and reliance on objective parameters, the RMH score may provide complementary prognostic information in this patient population; however, external validation in independent cohorts is required before broader clinical implementation can be considered.