Prognostic Impact of the Gustave Roussy Immune Score on Cancer-Specific Survival and Treatment Completion in Patients with Bladder Cancer

Background: Bladder cancer has diverse clinical outcomes, even in patients receiving curative treatment. Traditional clinicopathological indicators inadequately assess individual risk. The Gustave Roussy Immune Score (GRIm-score), which combines albumin, lactate dehydrogenase (LDH), and neutrophil-to-lymphocyte ratio (NLR), is a prognostic factor for solid tumors; however, its role in bladder cancer remains unclear. Methods: In this retrospective cohort study, patients with bladder cancer confirmed through histopathology received bladder-preserving multimodal therapy or radical cystectomy between October 2010 and April 2025. Participants were grouped into low (0–1) and high (2–3) GRImS categories for analysis. The study examined cancer-specific survival (CSS) and the secondary outcomes of progression-free survival (PFS), overall survival (OS), and treatment completion. Survival analyses were performed using the Kaplan–Meier method and Cox proportional hazard regression. Results: A total of 89 patients participated in the study, with 73 (82.0%) and 16 (18.0%) having low and high GRIm-Score. During a median follow-up of 21.5 months, patients with a high GRIm-score had significantly shorter PFS, OS, and CSS than those with a low GRIm-score. The median CSS was 14.07 months for the high GRIm-score group and 27.75 months for the low GRIm-score group (p = 0.004). In multivariable Cox regression analysis, a high GRIm-score was independently associated with an increased cancer-specific mortality risk (hazard ratio [HR] 2.48, 95% confidence interval [CI], 1.31–4.67; p = 0.005). Treatment completion was lower in the high GRIm-score group (31.3% vs. 64.4%, p = 0.031). Conclusions: The GRIm-score serves as an independent prognostic indicator for cancer-specific survival in patients with bladder cancer undergoing curative treatment and is related to therapy completion.