B. L. Ecker1, M. T. McMillan1, J. Datta1, D. L. Fraker1, G. C. Karakousis1, R. E. Roses1 1University Of Pennsylvania,Philadelphia, PA, USA
Introduction: The role of adjuvant chemotherapy (AC) in the treatment of small bowel adenocarcinoma is poorly defined. Previous analyses have been limited by small sample size and have failed to demonstrate a survival advantage.
Methods: Resected AJCC pathologic stage I-III small bowel adenocarcinoma patients receiving AC (n=1,637) or surgery alone (SA) (n=2,753) were identified in the National Cancer Data Base (1998–2011). Cox regression identified covariates associated with overall survival (OS). AC and SA cohorts were matched (1:1) by propensity scores based on the likelihood of receiving AC on multivariable analysis or hazard ratio on Cox modeling. Kaplan-Meier estimates of OS were compared.
Results: Omission of adjuvant chemotherapy conferred an increased risk of death (HR 1.36 95% CI 1.22–1.52, p<0.001). After propensity-score matching, median OS was superior in patients with AJCC stage III disease receiving AC compared with SA (n=1,217, 41.4 vs. 26.5 m, p<0.001), regardless of tumor location (duodenum: n=545, 36.3 vs. 25.7 m, p=0.002; jejunoileal: n=469, 47.9 vs. 30.0 m, p=0.015). Adjuvant chemotherapy was not associated with improved OS in patients with AJCC stage II disease (n=927, 116.7 vs. 92.1 m, p=0.410) regardless of tumor location (duodenal: n=235, 110.3 vs. 117.9 months, p=0.859; jejunoileal: n=450, 152.3 vs. 137.3 months, p=0.389), or the presence of putative high risk features including: poorly differentiated histology (n=254, 93.4 vs. 94.4 m, p=0.766), T4 tumor classification (n=291, 68.6 vs. 43.8 m, p=0.060), or a positive resection margin (n=62, 77.7 vs. 33.6 months, p=0.379). There was no OS benefit to adjuvant chemotherapy receipt for AJCC stage I patients (n=64, 116.6 vs. 102.1 months, p=0.843).
Conclusions: AC is associated with improved OS in AJCC stage III patients. The marked absolute OS advantage in patients with stage II disease and T4 tumors, or after positive margin resection, may justify use of AC in selected patients with earlier stage disease.