CLINICAL TOXICITY OF PERIPHERAL-NERVE TO INTRAOPERATIVE RADIOTHERAPY IN A CANINE MODEL

Purpose: The clinical late effects of intraoperative radiotherapy (IORT) on peripheral nerve were investigated in a foxhound model. Methods and Materials: Between 1982 and 1987, 40 animals underwent laparotomy with intraoperative radiotherapy of doses from 0-75 Gy administered to the right lumbosacral plexus, Subsequently, all animals were monitored closely and sacrificed to assess clinical effects to peripheral nerve, This analysis reports final clinical results of all animals, with follow-up to 5 years. Results: All animals treated with greater than or equal to 25 Gy developed ipsilateral neuropathy, An inverse relationship was noted between intraoperative radiotherapy dose and time to neuropathy, with an effective dose for 50% paralysis (ED(50)) of 17.2 Gy. One of the animals treated with 15 Gy IORT developed paralysis, after a much longer latency than the other animals. Conclusions: Doses of 15 Gy delivered intraoperatively may be accompanied by peripheral neuropathy with long-term follow-up, This threshold is less than that reported with shorter follow-up, The value of EDS, determined here is in keeping with data from other animal trials, and from clinical trials in humans.