Trends in incidence of small bowel cancer according to histology: a population-based study

Background Small bowel cancer is not a single entity. Population-based studies taking into account histological diversity are scarce. The aim of this study was to report on their trends in incidence by histology in France over the past 20 years. Methods All patients with a small bowel cancer diagnosed in 15 French administrative areas covered by a registry from the network of French cancer registries (FRANCIM) were included. Age-standardized incidence rates were estimated using the world standard population. Incidence rates were calculated by gender, age group, histology, and 5-year period. Results The overall age-standardized incidence rates were 1.46/100,000 inhabitants in men and 0.9/100,000 inhabitants in women. Adenocarcinoma was the most common histological type (38%), followed by neuroendocrine tumors (35%), lymphoma (15%) and sarcoma (12%). Age at diagnosis and tumor location differed between adenocarcinoma and neuroendocrine tumors. The incidence of all four tumor types increased significantly over the 20-year period, with the exception of lymphoma in men. The annual percentage change for neuroendocrine tumors was 3.89% in men and 3.61% in women; for sarcoma, it was 3.38% and 4.08%, respectively. The incidence of adenocarcinoma and lymphoma also increased in women with an annual percentage change of 3.05% and 3.32%, respectively. Conclusion Small bowel cancer incidence has increased over time. This increase occurred with different amplitudes and patterns in the four major histological types. The improvement in imaging techniques could partly explain this increase. It is necessary to determine whether predisposing conditions may contribute to this change.