Small Bowel Adenocarcinomas: Impact of Location on Survival.

Background: Proximal (duodenal) small bowel adenocarcinomas have a worse prognosis than distal (jejuno-ileal) tumors, but differences in patient, tumor, and treatment factors between locations remain unclear.
Methods: Patients in the National Cancer Database with surgically resected pathologic stage I-IV small bowel adenocarcinomas between 2004 and 2015 were analyzed. Clinical stage IV patients were excluded.
Results: Proximal tumors (n = 3767) were more likely to be higher grade (OR 1.52, CI 1.22-1.85 for moderately; OR 1.83, CI 1.49-2.33 for poorly differentiated, P < 0.01 for both) and have positive lymph nodes (OR 2.04, CI 1.30-3.23, P < 0.01), while distal tumors (n = 3252) were likely to be larger (OR 1.31, CI 1.07-1.60 for size > 5 cm, P < 0.01). Proximal tumors were associated with worse overall survival (OS) and stage-specific survival compared with distal tumors (all P < 0.01). Cox regression analysis of the entire cohort showed worse survival with community versus academic cancer programs, higher comorbidity scores, pathologic stage IV, poorly differentiated histology, positive nodal or margin status, and proximal location, while female gender, larger tumor size, and chemotherapy predicted better survival. On separate Cox regression analyses of each location, neoadjuvant chemotherapy was associated with better OS in the proximal cohort (HR 0.70, CI 0.55-0.88, P < 0.01), while adjuvant chemotherapy was associated with better OS for both proximal (HR 0.49, CI 0.42-0.57, P < 0.01) and distal tumors (HR 0.68, CI 0.57-0.81, P < 0.01).
Conclusions: Proximal small bowel adenocarcinomas are associated with worse overall and stage-specific survival. This may be due to tumor biologic differences as proximal tumors were more likely to have higher grade. Future studies should further investigate differences between proximal and distal tumors to guide targeted treatment algorithms.
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