Novel Risk Scoring System for Patients with Metastatic Castration Resistant Prostate Cancer Treated with Lutetium-177-PSMA-617.

Abstract

PurposeLutetium-177(177Lu)-PSMA-617 improves survival for patients with metastatic castration-resistant prostate cancer (mCRPC), but outcomes are heterogeneous and standardized risk stratification tools are lacking. We developed a novel risk stratification tool for patients treated with 177Lu-PSMA-617.MethodsWe conducted a retrospective analysis of 163 patients at Emory Winship Cancer Institute. Four prognostic models using Cox proportional hazards models were constructed using best-subset variable selection and integrated into a composite model.ResultsAmong 163 patients (52% White, 44% Black; 80% previous taxane use) body mass index (BMI) decline during treatment was associated with shorter progression-free survival (PFS) and overall survival (OS) (HR = 1.75, p = 0.03; HR = 2.35, p = 0.031). Higher subcutaneous adipose tissue index (SATI)/skeletal muscle index (SMI) was independently associated with improved OS (HR = 0.5, p = 0.019), whereas higher visceral adipose tissue index (VATI)/SATI was independently associated with worse OS (HR = 2.62, p = 0.005). A body composition-based prognostic score identified VATI/SATI, SMI, and total adiposity as the strongest OS predictors (C = 0.629). The composite score incorporating inflammatory biomarkers and body composition demonstrated good discrimination (C-index = 0.732) and effectively stratified patients by PFS and OS. For PFS, relative risks across increasing risk quartiles were 0.34, 0.40, and 0.62 in comparison to the highest risk quartile (p = 0.034). For OS, corresponding hazard ratios were 0.15, 0.19, and 0.54 (p = 0.003).ConclusionsA risk score incorporating body composition and inflammatory biomarkers demonstrates prognostic value for patients treated with 177Lu-PSMA-617.