Pre-treatment Tumor Volume Growth Rate and Baseline Volume Measured by an Artificial Intelligence Program Predict Overall Survival in Patients With Pleural Mesothelioma Undergoing Deferred Systemic Therapy.

INTRODUCTION: The optimal timing of systemic therapy in pleural mesothelioma remains debated, particularly for asymptomatic patients with a limited disease burden. Prior studies suggest that deferred treatment may not compromise overall survival (OS) in selected patients. Reliable prognostic markers to guide treatment timing are lacking. We investigated whether baseline tumor volume and pretreatment tumor growth rate, quantified using an artificial intelligence (AI)-based model, predict OS in patients deferring systemic therapy. METHODS: We conducted a single-center retrospective study including patients with pleural mesothelioma diagnosed between 2010 and 2025 who deferred systemic therapy for more than or equal to 3 months and had at least two pretreatment computed tomography scans. Total tumor volume and tumor growth rate (mL/mo) were automatically measured using the AI-based ARTIMES model. Optimal cutoffs were determined using receiver operating characteristic analysis. OS was analyzed using Kaplan-Meier estimates and Cox proportional hazards models. RESULTS: A total of 71 patients were included (median age 66.8 y; 80.3% male; Eastern Cooperative Oncology Group 0-1). The median deferral time was 8.0 months. Optimal cutoffs were 56.5 mL for baseline tumor volume and 67.8 mL/mo for tumor growth rate. Patients with a low baseline tumor volume had a significantly longer median OS compared with those with a high volume (30.95 versus 16.89 mo; p = 0.0066). Similarly, a low tumor growth rate was associated with improved OS (29.40 versus 14.59 mo; p = 0.00057). In multivariable analysis, sarcomatoid histology remained independently associated with worse OS (hazard ratio = 3.28, 95% confidence interval: 1.38-7.75, p = 0.007). CONCLUSIONS: AI-derived baseline tumor volume and tumor growth rate are strong prognostic factors for OS in patients with pleural mesothelioma deferring systemic therapy. Patients with low baseline tumor volume and those with low tumor growth rate were significantly associated with a longer OS.