SMALL-BOWEL RADIATION-INJURY - RADIOBIOLO GICAL AND RADIOPATHOLOGICALASPECTS, RISK-FACTORS AND PREVENTION

Small bowel radiolesions are a doss-limiting factor in radiotherapy of the abdomen ether administered alone or in combination with surgery a nd/or chemotherapy. Acute radiolesions on the small intestine are freq uent and related to the rapid turnover of mucosal cells. The acute eff ects of radiation are rapidly regressive after completion of radiation therapy. The reported incidence of severe late chronic radiation inju ry of the small intestine varies between 0.5 and 15%. Most of chronic injuries occur between 12 and 24 months after radiation, Chronic radia tion enteropathy is related to the low turnover of the intestinal wall tissues. It is caracterized by progressive cell depletion, collagen f ibrosis and obliterative vascular injury. The main factors predisposin g to late small bowel complications are: the total radiation dose: the dose per fraction, the volume of small bowel irradiated, previous sur gery: and chemotherapy combined to radiation therapy. The knowledge of the predisposing conditions of chronic small bowel injuries facilitat es estimation of late small bowel potential morbidity and allows the p roposal of personalised therapeutic adjustments to reduce this risk.