Prognostic stratification of metastatic gastroenteropancreatic neuroendocrine neoplasms by 18F-FDG PET: feasibility of a metabolic grading system

• Published in: The Journal of nuclear medicine (1978) Vol. 55; no. 8; pp. 1260 - 1266
• Main Authors: Ezziddin, Samer, Adler, Linda, Sabet, Amir, Pöppel, Thorsten Dirk, Grabellus, Florian, Yüce, Ali, Fischer, Hans-Peter, Simon, Birgit, Höller, Tobias, Biersack, Hans-Jürgen, Nagarajah, James
• Format: Journal Article
• Language: English
• Published: United States 01.08.2014
• Subjects: Adult; Aged; Aged, 80 and over; Feasibility Studies; Female; Fluorodeoxyglucose F18; Gastrointestinal Neoplasms - diagnostic imaging; Gastrointestinal Neoplasms - metabolism; Gastrointestinal Neoplasms - pathology; Humans; Ki-67 Antigen - metabolism; Male; Middle Aged; Neoplasm Grading; Neoplasm Metastasis; Neuroendocrine Tumors - diagnostic imaging; Neuroendocrine Tumors - metabolism; Neuroendocrine Tumors - pathology; Pancreatic Neoplasms - diagnostic imaging; Pancreatic Neoplasms - metabolism; Pancreatic Neoplasms - pathology; Positron-Emission Tomography; Prognosis; Retrospective Studies; Survival Analysis; prognostic stratification; 18F-FDG; tumor grading; neuroendocrine tumors; PET/CT; gastroenteropancreatic
• ISSN: 1535-5667
• DOI: 10.2967/jnumed.114.137166

The tumor proliferation marker, Ki-67 index, is a well-established prognostic marker in gastroenteropancreatic neuroendocrine neoplasms (NENs). Noninvasive molecular imaging allows whole-body metabolic characterization of metastatic disease. We investigated the prognostic impact of (18)F-FDG PET in inoperable multifocal disease. Retrospective, dual-center analysis was performed on 89 patients with histologically confirmed, inoperable metastatic gastroenteropancreatic NENs undergoing (18)F-FDG PET/CT within the staging routine. Metabolic (PET-based) grading was in accordance with the most prominent (18)F-FDG uptake (reference tumor lesion): mG1, tumor-to-liver ratio of maximum standardized uptake value ≤ 1.0; mG2, 1.0-2.3; mG3, >2.3. Other potential variables influencing overall survival, including age, tumor origin, performance status, tumor burden, plasma chromogranin A (≥600 μg/L), neuron-specific enolase (≥25 μg/L), and classic grading (Ki-67-based) underwent univariate (log-rank test) and multivariate analysis (Cox proportional hazards model), with a P value of less than 0.05 considered significant. The median follow-up period was 38 mo (95% confidence interval [CI], 27-49 mo); median overall survival of the 89 patients left for multivariate analysis was 29 mo (95% CI, 21-37 mo). According to metabolic grading, 9 patients (10.2%) had mG1 tumors, 22 (25.0%) mG2, and 57 (64.8%) mG3. On multivariate analysis, markedly elevated plasma neuron-specific enolase (P = 0.016; hazard ratio, 2.9; 95% CI, 1.2-7.0) and high metabolic grade (P = 0.015; hazard ratio, 4.7; 95% CI, 1.2-7.0) were independent predictors of survival. This study demonstrated the feasibility of prognostic 3-grade stratification of metastatic gastroenteropancreatic NENs by whole-body molecular imaging using (18)F-FDG PET.