ELECTRON-BEAM INTRAOPERATIVE RADIATION-THERAPY FOR PEDIATRIC NEOPLASMS

Background. Intraoperative radiation therapy (IORT) has potential adva ntages over conventional external beam radiation in that a single larg e dose is delivered to the tumor and its regional bed at the time of s urgical exploration. The therapeutic ratio is enhanced by direct tumor visualization, precise treatment volume, and exclusion of normal orga ns. In childhood, local tumor control is critical for lesions that can not be totally excised or residual disease not ablated by systemic the rapy. Methods. During the past decade, the authors evaluated IORT in p ediatric patients with unresectable or recurrent tumors. Fifty-nine pa tients were treated, 48 for advanced malignant disease and 11 for hist ologically benign but locally aggressive tumors. Sixty-four operations were performed, during which 84 separate radiation fields were used. High energy electrons at 5-11 MeV were delivered at a dose of 1000-170 0 cGy to a tissue depth of 0.5-3 cm. Results. Of 25 children with adva nced neuroblastoma, 15 were alive 14-104 months (mean, 51 months) afte r treatment. The survival of all patients with solid malignancies was 63%. Local tumor control was achieved in 75% of children with cancer a nd 91% of those with benign tumors. Complications of IORT at the doses used were trivial. Conclusions. Electron beam therapy can be safely a nd efficiently delivered to young patients during operations intended to treat the primary tumor. The outcome achieved for overall survival and local control of the primary tumor is encouraging, and an acceptab le complication rate during intermediate to long-term follow-up has be en noted.