A natural history of gastroenteropancreatic neuroendocrine tumors evaluated at a tertiary cancer center: An observational study of 2,067 cases.

Abstract

508 Background: Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are the second most prevalent digestive cancer and are increasing in incidence. With relatively indolent tumor growth, survival is often long, even for patients with metastatic disease. However, few studies have assessed long-term survival. Therefore, we analyzed the overall survival (OS) of a cohort of GEP-NET patients at a tertiary cancer center from 2000-2015. Methods: 2,707 patients with a pathologic diagnosis of GEP-NET were identified. 640 patients presented for second-opinion visits and were excluded, leaving 2,067 patients, of whom, 2,053 had vital status data for analysis. Primary sites included jejunum/ileum (small bowel), pancreas, gastric, colorectum, appendix, duodenum, and unknown. OS time was calculated from the date of pathologic diagnosis to the date of last follow-up or death. The reverse Kaplan-Meier method was used to calculate follow-up time. Vital status was identified through linkage to the Florida Cancer Registry. Kaplan-Meier (KM) curves and log-rank test were used for OS analyses. Results: The median age of the cohort was 60.7 years. The median follow-up time was 148.9 months (12.4 years). 1,431 (69.2%) patients presented with distant metastatic disease. Most patients, 1,351 (65.5%), underwent treatment at another facility before presentation. The median OS was 132.2 months (11.0 years) for the cohort and was 108.0 and 245.5 months for patients presenting with and without metastasis, respectively (p < 0.001). For metastatic patients, unknown primary tumor site was associated with the worst median OS (55 months), followed by rectal (77 months), gastric (84 months) and pancreatic (85 months; p < 0.001). Duodenal and small bowel had the longest median OS at 147 and 143 months, respectively. Surgery for metastatic disease had an OS benefit (155.7 months) compared to no surgery (98.3 months). Conclusions: In a large cohort of predominantly metastatic GEP-NET patients with extended follow-up time, median OS was over 11 years and 9 years for patients with metastatic disease. These results suggest that OS at a tertiary cancer center may be greater than historical national administrative analyses when given adequate follow-up time, which is important to avoid bias in survival estimates.[Table: see text]