The evolving role of imaging for small bowel neuroendocrine neoplasms: estimated impact of imaging and disease-free survival in a retrospective observational study

Purpose To determine how small bowel neuroendocrine neoplasms (SBNEN's) are diagnosed and examine the effect of CT enterography (CTE) on diagnosis and rates of disease-free survival. Methods Histopathologically-confirmed SBNEN's diagnosed at our institution between 1996 and 2016 were identified. Clinical presentation, radiology, endoscopy, surgery, and pathology reports were reviewed and compared between consecutive 5-year periods. Results Of the 178 SBNEN initially diagnosed at our institution, the incidence increased 12-fold from 9 (during 1996-2000) to 114 (during 2011-2016). Comparing the first 5 to the last 5 years, GI bleeding and abdominal pain increased significantly as indications (with both increasing from 0 to > 25%, p <= 0.023). Initial diagnosis by radiology increased 2-fold [from 33% (n = 3) to 66% (n = 75); p = 0.263]. Detection of a small bowel mass and the suggestion that SBNEN was present varied significantly between imaging modalities (p < 0.0001; CTE - 95% (52/55) and 91% (50/55) vs. abdominal CT 45% (37/85) and 35% (29/85), respectively). Recurrence rates increased with SBNEN size (p = 0.012; e.g., of SBNEN diagnosed by endoscopy, 18% of SBNEN measuring 0.6 +/- 0.3 cm recurred vs. 75% measuring 3.7 +/- 1.0 cm). Rates of disease-free survival, and the incidence of local and liver metastases were decreased when tumors were first identified by CTE rather than other CT/MR imaging modalities (p = 0.0034, 0.0475, and 0.0032, respectively). Conclusion There has been a dramatic increase in SBNENs detected by CTE and endoscopy over the last 20 years. SBNEN's detected by CTE and small tumors detected at endoscopy have longer disease-free survival after surgical resection.