Beagle model used in a tissue tolerance study of the response of normal and surgically manipulated liver to single high-dose intraoperative radiotherapy

To investigate the feasibility of delivering a single large dose of intraoperative electron beam radiotherapy (IORT) to the liver of clinically normal and partially hepatectomized beagles, an experimental study was designed, The purpose of the study was to obtain dose guidelines for the delivery of IORT to the liver of human patients with colorectal cancer metastases to the liver, After partial resection of the liver, IORT in doses up to 30 Gy was applied to the resection plane as well as to a nonsurgically manipulated part of the liver of 25 beagles, The temporal sequence of histologic changes of these irradiated parts of the liver tissue was investigated, There were no postoperative complications and no morbidity or mortality associated with a minimal follow-up of 3 years, Necropsy performed 3 months after IORT revealed only mild histopathologic changes, One year after IORT, more distinct histopathologic changes consisting of capsular thickening, diffuse parenchymal fibrosis, and subcapsular hepatocellular atrophy were found, Three years after IORT, the parenchymal architecture seemed to be restored, although loss of liver tissue was definitive at the irradiation site; liver function remained intact, These results indicate that IORT to part of the liver in the canine model can be safely applied and that, although doses up to 30 Gy can result in severe local tissue damage, wound healing and liver function are not disturbed