Neuroendocrine Tumors of Gastrointestinal Tract and the Pancreas: Diagnostic Modalities, Accuracy, and Outcomes

Abstract

Purpose: The aim of the study was to evaluate the utility of various diagnostic modalities including computed tomography (CT) scan, endoscopy, and endoscopic ultrasound (EUS) in gastrointestinal (GI) neuroendocrine tumors (NET). Methods: Retrospective chart review of patients who underwent endoscopic evaluation from January 2003 to June 2009 at a cancer center was done. The accuracy of EUS-guided fine needle aspiration (FNA) was evaluated. The T- and N- staging of NET by EUS was compared to histological staging. Results: Results: A total of 85 patients (35 men) with a mean age 60.3 years were found to have GI NET. There were 50 patients with pancreatic endocrine neoplasm (PEN) including 5 with multiendocrine neoplasia 1 (MEN1), 15 with duodenal carcinoids, 2 ampullary carcinoids, 12 gastric carcinoids, 3 rectal carcinoids, 1 ileal carcinoid, 2 NET of unknown primary. Among PEN, 5 were in the uncinate process, 14 in the head, 3 in the neck, 8 in the body, and 15 in the tail, and 5 MEN1. The median size was 2.3 cm (range; 0.52-7 cm) for PEN, 1cm (range; 0.6-7 cm) for gastric carcinoids, 1cm (range; 0.5-3 cm) for duodenal carcinoids, and 1.8 cm (range; 0.5-3.1 cm) for rectal carcinoids. EUS was performed in 78 patients. The CT findings were unremarkable in 25, positive for a mass in 26, and metastasis in 30. For patients with no abnormalities seen on CT scan (25 patients), upper endoscopy (EGD) and sigmoidoscopy showed a discrete nodule or lesion in all patients. 46 had EUS for PEN; EUS FNA was performed in 33 and all were positive (accuracy 100%). EUS staging was compared to histologic staging for carcinoids and the accuracy for T-staging was 61% (if T1a and T1b were separated, accuracy was 52%) with understaging of 13% and overstaging of 26%. All carcinoids smaller than 1cm in the stomach (2), duodenum (3), and rectum (1) did not progress after endoscopic resection and/or biopsy during a median follow-up period of 92 days (range 24-758). No complications were seen in endoscopic procedures. Conclusion: Endoscopic evaluation is the most sensitive modality in detecting and diagnosing carcinoids smaller than 1cm. EUS FNA is highly accurate in the diagnosis of PEN. EUS is moderately accurate in T-staging of carcinoids. Carcinoids, smaller than 1cm in the stomach, duodenum, and rectum, may not have an aggressive behavior in a short term follow-up period.