FDG-PET/CT SUVmax Predicts Recurrence Risk of Resected Pleuropulmonary Solitary Fibrous Tumors

Risk stratification of pleuropulmonary solitary fibrous tumors (SFTs) is based on post-resection histopathologic scoring systems. We queried whether preoperative 18-fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) maximum standardized uptake values (SUVmax) had prognostic value for recurrence or metastasis.

Retrospective review of patients who underwent FDG-PET/CT before resection of SFT between January 2002 and June 2023. Independent review of slides by a pulmonary pathologist and radiologist review of FDG-PET/CT were performed. Statistical analyses included nonparametric tests for correlations, receiver-operating characteristic (ROC) curves, and Kaplan-Meier analysis.

There were 34 patients with a preoperative FDG-PET/CT before SFT resection. Median tumor SUVmax was 2.3 (range: 0.9-38.7). Recurrence occurred in five patients (14.7%) (three local, two metastatic). Tumor SUVmax was associated with tumor size (p < 0.001), parietal pleural origin (p = 0.027), hypercellularity (p = 0.049), mitoses (p < 0.001), and Ki67 (p = 0.015). SUVmax correlated with the modified Demicco score (p < 0.001) and Tapias score (p < 0.001). Prediction of recurrence was excellent with SUVmax (area under ROC curve [AUC] = 0.872, p < 0.001), Tapias score (AUC = 0.914, p < 0.001), and modified Demicco score (AUC = 0.821, p < 0.001). Time-dependent ROC analysis identified SUVmax more than or equal to 2.4 as high risk for recurrence. Recurrence-free survival at 1, 3, 5, and 10 years was 92.9%, 83.6%, 69.6%, and 46.4%, respectively, in patients with SUVmax more than or equal to 2.4, but it was 100% at all time points with SUVmax less than 2.4 (p = 0.002). SUVmax was not associated with overall survival in this small cohort.

Tumor metabolic activity on FDG-PET/CT is predictive of SFT recurrence. Preoperative SUVmax correlates with known histopathologic high-risk features and validated risk scores. Preoperative FDG-PET/CT should be performed before SFT resection to assist in prognostication.