Treatment and Survival of Small-bowel Adenocarcinoma in the United States: A Comparison with Colon Cancer

BACKGROUND: Small-bowel adenocarcinoma is rare and fatal. Because of data paucity, there is a tendency to extrapolate treatment from colon cancer, particularly in the adjuvant stetting. OBJECTIVE: The purpose of this study was to evaluate the current surgical and adjuvant treatments of small-bowel adenocarcinoma and compare with colon cancer. DESIGN: This was a retrospective cohort study. SETTINGS: The linked Surveillance, Epidemiology, and End Results and Medicare database was used at a tertiary referral hospital. PATIENTS: Patients with small-bowel adenocarcinoma and colon cancer identified from 1992 to 2010, using International Classification of Diseases for Oncology, 3^rd Revision, site, behavior, and histology codes were included. MAIN OUTCOME MEASURES: Overall survival and cancer-specific survival were estimated using the Kaplan-Meier method and competing risk analysis. RESULTS: A total of 2123 patients with small-bowel adenocarcinoma and 248,862 patients with colon cancer were identified. Five-year overall survival rates for patients with small-bowel adenocarcinoma and colon cancer were 34.9% and 51.5% (p < 0.0001). A total of 1550 patients with small-bowel adenocarcinoma (73.0%) underwent surgery, compared with 177,017 patients with colon cancer (71.1%). The proportion of patients who received chemotherapy was similar, at 21.3% for small bowel and 20.0% for colon. In contrast to colon cancer, chemotherapy did not improve overall or cancer-specific survival for patients with small-bowel adenocarcinoma, regardless of stage. Predictors of poor survival for small-bowel adenocarcinoma on multivariate analysis included advanced age, black race, advanced stage, poor tumor differentiation, high comorbidity index, and distal location. Chemotherapy did not confer additional survival benefit compared with surgery alone (HR, 1.04 (95% CI, 0.90-1.22)). LIMITATIONS: This was a retrospective review. The reliance on Medicare data limited granularity and may have affected the generalizability of the results. CONCLUSIONS: The prognosis for small-bowel adenocarcinoma is worse than that for colon cancer, and only surgery improves survival. In contrast to colon cancer, a survival benefit from current chemotherapy regimens for small-bowel adenocarcinoma is not seen, suggesting that it may be overused and needs more rigorous study.