Prognostic Value of the SUVmax-IPI Composite Score on Overall Survival in Metastatic Prostate Cancer

Objective: This study aimed to evaluate the prognostic value of the SUVmax-IPI composite score, generated by integrating the maximum standardized uptake value (SUVmax) derived from metastatic ⁶⁸Ga-PSMA PET/CT imaging with the inflammatory prognostic index (IPI), in predicting overall survival in patients with metastatic prostate cancer. Materials and Methods: This retrospective, single-center cohort study included 146 patients diagnosed with metastatic prostate adenocarcinoma between 2009 and 2025. Among them, 125 patients with available PET/CT imaging were included in the SUVmax-IPI analysis. The composite score was calculated by multiplying the metastatic SUVmax value by the IPI. The optimal cut-off value was determined using receiver operating characteristic curve analysis. Overall survival was evaluated using the Kaplan-Meier method and compared using the log-rank test. Independent prognostic factors were identified using multivariable Cox proportional hazards regression analysis with a forward (stepwise) selection approach. Results: Using the predefined cut-off value (82), the median overall survival was 125 months in patients with SUVmax-IPI ≤ 82 and 19 months in those with SUVmax-IPI > 82 (log-rank p = 0.001). In the forward multivariable Cox regression model, SUVmax-IPI > 82 remained independently associated with worse overall survival after adjustment for ALP, AST, PSA nadir, and androgen deprivation modality (hazard ratio [HR]: 7.92; 95% confidence interval [CI]: 2.97-21.10; p < 0.001). Conclusions: The SUVmax-IPI composite score, integrating PSMA PET/CT-derived metabolic tumor activity with systemic inflammatory burden, is independently associated with overall survival in metastatic prostate cancer. These findings suggest that combining metabolic and inflammatory parameters may enhance prognostic stratification beyond conventional clinical and biochemical markers.