To Örebro University

Background: Small bowel adenocarcinoma (SBA), neuroendocrine tumors (NET) and gastrointestinal stromal tumors (GIST) are neoplastic lesions of the small bowel while small bowel adenomas are precursors of SBA.

Aim: To examine mortality in patients diagnosed with SBA, small bowel adenomas, NET and GIST.

Methods: We performed a population-based matched cohort study encompassing all individuals with SBA (n = 2289), adenomas (n = 3700), NET (n = 1884) and GIST (n = 509) in the small bowel diagnosed at any of Sweden's 28 pathology departments between 2000 and 2016 (the "ESPRESSO study"). Each case was matched by sex, age, calendar year and county of residence to up to 5 comparators from the general population. Through Cox regression we estimated hazard ratios (HRs) and 95% confidence intervals (95%CIs) for death and cause-specific death adjusting for education.

Results: During follow-up until December 31, 2017, 1836 (80%) deaths occurred in SBA patients, 1615 (44%) in adenoma, 866 (46%) in NET and 162 (32%) in GIST patients. This corresponded to incidence rates of 295, 74, 80 and 62/1000 person-years respectively and adjusted HRs of 7.60 (95%CI=6.95-8.31), 2.21 (2.07-2.36), 2.74 (2.50-3.01) and 2.33 (1.90-2.87). Adjustment for education had a substantial impact on the HR for death in SBA but not for other neoplasias. The predominant cause of excess death was cancer in all groups.

Conclusion: This study confirms earlier findings of increased death rates in patients with SBA and NET in a modern study population. We also demonstrate a more than 2-fold increased risk of death in both GIST and the SBA precursor adenoma.