Predictive value of 18F-FDG PET and somatostatin receptor scintigraphy in patients with metastatic endocrine tumors

Abstract

The treatment of metastatic neuroendocrine tumors depends the aggressiveness of the disease. We wanted to know whether 18F-FDG PET and somatostatin receptor scintigraphy (SRS) predict early disease progression and patient survival. Methods: We undertook a prospective study of patients with metastatic neuroendocrine tumor diagnosed between September and January 2006. After obtaining signed informed consent from the patients, we performed CT, SRS, and 18F-FDG and reviewed histologic data. CT was repeated every 3mo assess the risk of early progressive disease (first 6 mo), progression-free survival, and overall survival. Results: Thirty-patients (mean age, 60 ± 15 y) were included. Histologically, patients had a high-grade and 34 a low-grade tumor. The results of 18F-FDG PET and SRS were positive in 15 and 27 patients. 2-y overall survival and progression-free survival were 73% 45%; 16 patients had early progressive disease. Most 18F-PET-positive patients had early progressive disease (14/15, 2/23 18F-FDG PET-negative patients), and most SRS-negative patients had early progressive disease (9/11, vs. 7/27 SRS-positive patients); 18F-FDG PET gave excellent negative positive predictive values of 91% and 93%; 18F-FDG PET results correlated with progression-free survival (P < 0.001) and overall survival (P < 0.001) even when only low-grade tumors were considered. SRS was associated with progression-free survival 0.001) and overall survival (P < 0.03). At multivariate analysis, only 18F-FDG PET was predictive of progression-free survival. Conclusion: 18F-FDG PET exhibits excellent predictive values for early tumor progression. 18F-FDG PET and SRS results correlate with progression-free survival and overall survival even histologically low-grade tumors. These explorations could included in the initial work-up for metastatic neuroendocrine tumor. Copyright © 2009 by the Society of Nuclear Medicine, Inc.