Fractionated irradiation of the regenerated rat liver.

Fractionated radiation therapy after liver resection for metastatic cancer has traditionally been a palliative procedure. Here, we consider that radiation may be an appropriate adjuvant therapy for cure after liver resection for metastases. This pilot study in rats establishes a model for evaluating the effects of fractionated irradiation posthepatectomy. Sixty Sprague-Dawley rats were randomized to four groups. The groups underwent laparotomy, laparotomy and radiation, hepatectomy, and hepatectomy and radiation. We found that the rats treated with radiation had statistically significant (P < 0.0001) clinical radiation change by liver function tests at 6 months. This damage was resolved to normal at 1 year regardless of hepatectomy. In fact, we demonstrate the possibility of a protective effect from radiation damage in the regenerated liver. We also demonstrate statistically significant histologic change at 8 months (P < 0.01) in the radiation-treated rats which does not resolve at 1 year.