Short- and long-term histopathological changes in the canine liver following single high-dose intraoperative...

The histopathological changes in the canine liver following single high-dose intraoperative radiation therapy (IORT) were investigated in order to establish the tolerance of liver tissue to IORT, thus providing a framework for clinical IORT treatment of patients with metastatic disease to the liver.

Following partial resection of the liver, IORT in doses of 10, 20, 25, or 30 Gy was applied to the resection plane and a non-surgically manipulated part of the liver of 25 beagles.

There were no postoperative complications, and no morbidity or mortality during a maximal follow-up of 5 years. Dogs were killed at 3 months, and 1, 2, 3 and 5 years following IORT. Light microscopic examination revealed capsular thickening, severe parenchymal fibrosis, liver cell atrophy, and bile duct proliferation at the irradiated area 1 2 years following IORT. At 3-5 years, however, only mild parenchymal changes were found that consisted of slight periportal fibrosis, an incidental portal-central fibrous septum and vascular changes with endothelial proliferation and focal arteriolar hyalinosis.

This study demonstrated that following partial hepatic resection, IORT to the liver in the canine model can be applied safely, without short- or long-term treatment morbidity. Although doses up to 30Gy resulted in severe local tissue damage 1-2 years following IORT, these changes were largely reversible due to hepatic regeneration.