[Radiation injury of the small intestine. Radiobiological, radiopathological aspects; risk factors and prevention].

Small bowel radiolesions are a dose-limiting factor in radiotherapy of the abdomen ether administered alone or in combination with surgery and/or chemotherapy. Acute radiolesions on the small intestine are frequent and related to the rapid turnover of mucosal cells. The acute effects of radiation are rapidly regressive after completion of radiation therapy. The reported incidence of severe late chronic radiation injury of the small intestine varies between 0.5 and 15%. Most of chronic injuries occur between 12 and 24 months after radiation. Chronic radiation enteropathy is related to the low turnover of the intestinal wall tissues. It is characterized by progressive cell depletion, collagen fibrosis and obliterative vascular injury. The main factors predisposing to late small bowel complications are: the total radiation dose, the dose per fraction, the volume of small bowel irradiated, previous surgery, and chemotherapy combined to radiation therapy. The knowledge of the predisposing conditions of chronic small bowel injuries facilitates estimation of late small bowel potential morbidity and allows the proposal of personalised therapeutic adjustments to reduce this risk.