Small bowel cancer in the United States: changes in epidemiology, treatment, and survival over the last 20 years.

Background: Previous studies have shown an increasing incidence of small bowel tumors in the United States. Our objective was to assess this increase by examining changes in histology-specific incidence, treatment, and survival.
Methods: Patients with small bowel malignancies were identified from the National Cancer Data Base (NCDB, 1985-2005) and the Surveillance Epidemiology and End Results (SEER, 1973-2004) database. Age-adjusted incidence rates were calculated using SEER. Treatment and survival trends over time were examined using the National Cancer Data Base. Regression models were developed to assess survival over time.
Results: Sixty-seven thousand eight hundred forty-three patients were identified with small bowel malignancies: 37.4% carcinoid, 36.9% adenocarcinomas, 8.4% stromal tumors, and 17.3% lymphomas. From 1973 to 2004, the incidence of carcinoid tumors increased more than 4-fold (2.1 to 9.3 per million), whereas changes in adenocarcinomas, stromal tumors, and lymphomas were less pronounced. From 1985 to 2005, utilization of surgery increased significantly for carcinoid tumors from 78.8% to 87.4% (P < 0.0001). Adjuvant chemotherapy utilization for adenocarcinoma increased from 8.1% in 1985 to 23.8% in 2005 (P < 0.0001). Treatment over time was generally unchanged for lymphoma and stromal tumors. Five-year survival after resection remained unchanged over time for all histologic subtypes even after adjusting for changes in patient demographics, tumor characteristics, and treatment approaches.
Conclusions: The overall incidence of small intestine malignancies has increased considerably, primarily because of carcinoid tumors which are now the most common small bowel cancer. With current treatments, survival has remained relatively unchanged over the last 20 years. Novel therapeutic options need to be investigated.