Prognostic indicators of recurrence after surgical resection in non-pancreatic gastrointestinal neuroendocrine tumors.

Abstract

e16287 Background: The incidence of gastrointestinal neuroendocrine tumors (GI-NETs) has continued to increase over the last two decades. In patients with locoregional disease, surgical resection of the primary tumor without additional therapies is considered standard of care. The frequency and risk factors associated with recurrence and survival in patients with non-pancreatic GI-NETs are poorly defined. We aimed to evaluate clinical and pathological factors associated with recurrence and survival in patients with resected non-pancreatic GI-NETs. Methods: We conducted a retrospective review of patients who presented to the Johns Hopkins Hospital between 2000-2019 with locoregional small bowel, colon, appendiceal, and rectal neuroendocrine tumors who underwent surgical resection with curative intent. We collected clinical and pathological data including tumor primary site, tumor differentiation, grade using Ki-67 labeling index (grade 1, 2, or 3), margin involvement, perineural or vascular invasion, time of recurrence, patterns of recurrence, and death. Patients with metastatic disease at the time of diagnosis and insufficient follow up were excluded. Results: A total of 133 patients met inclusion criteria. Most patients had tumors originating from the small bowel (n = 87, 66%), followed by the appendix (n = 19, 15%), rectum (n = 18, 14%), and colon (n = 7, 5%). With a median follow-up of 35 months, 23 patients (17%) had tumor progression after curative-intent surgery, with the liver (n = 13, 57%) as the most common site. In the majority of patients, tumors were well-differentiated (n = 118, 97%) and grade 1 (n = 78, 75%). Intermediate/high grade tumors (grade 2/3) occurred in 26 (25%) of patients. Median progression-free survival was 226 months (18.8 years). Age (greater than 60) and intermediate/high grade tumors (grade 2 or 3) were associated with worse overall survival HR = 5.5 (95% CI: 1.5, 19.6), p = 0.009, and HR = 3.3 (95% CI: 1.1, 10.2), p = 0.034, respectively. Tumor grade (2 or 3) and positive nodes were associated with worse progression-free survival HR = 4.5 (95% CI: 2.0, 10.1), p = 4e-04, and HR = 3.1 (95% CI: 1.4, 6.8), p = 0.009, respectively. Conclusions: A significant number of patients (17%) with non-pancreatic GI-NETs had tumor progression after curative-intent surgery. Risk factors for recurrence include intermediate/high-grade tumors and positive lymph nodes. Further studies are needed to evaluate the role of adjuvant therapy in patients at higher risk of recurrence following surgical resection for non-pancreatic GI-NETs.