Prognostic Value of Volume-Based Metabolic Parameters Measured by 18F-FDG PET/CT of Pancreatic Neuroendocrine Tumors

Abstract

Purpose To date, the prognostic value of 18F-FDG PET/CTfor patients with pancreatic neuroendocrine tumors (PNETs)has not been well characterized.We investigated the prognosticvalue of volumetric parameters using 18F-FDG PET/CT inthis patient population. Methods We retrospectively reviewed 20 cases of pathologicallyproven PNET in patients who had undergone pretherapeutic18F-FDG PET/CT. PET parameters includingmaximum and average standardized uptake values (SUVmax,SUVave), metabolic tumor volume (MTV), and total lesionglycolysis (TLG) of the primary tumor were measured using athreshold SUV to determine the boundaries of the tumors. Univariate and multivariate survival analyses were performedwith adjustments for PET parameters and other clinicalvalues. Results The median clinical follow-up was 22.3 (range, 1.2–95.4) months. Cancer-related death occurred in 5 of 20patients (25 %). Patients had clinical or pathological stagesof I in seven patients, II in six patients, III in three patient, andIV in four patients. According to the WHO histological classificationof subtypes, 3 patients exhibited well-differentiatedPNETs, 13 patients had well-differentiated endocrine carcinomas,and 4 had poorly differentiatedendocrine carcinomas. Univariate analysis showed that tumor size (p=0.028), AJCCstage (p=0.009), T stage (p=0.028), M stage (p=0.029),treatment modality (p=0.045), MTV (p=0.003) and TLG(p=0.027) were significant predictors of overall survival. Onmultivariate analysis, MTV (HR=10.859, p=0.031) was asignificant independent predictor of overall survival alongwith the AJCC stage (HR=11.556, p=0.027). Conclusion In patients with PNETs, the MTVof the primarytumor asmeasured by 18F-FDG PET/CTalong with the AJCCstage may be a significant independent prognostic factor foroverall survival.