HIGH-DOSE-RATE INTRAOPERATIVE RADIATION-THERAPY FOR PEDIATRIC SOLID TUMORS

Background. Sixteen pediatric patients with solid tumors received trea tment on a protocol designed to test the feasibility and safety of hig h-dose rate intraoperative radiation therapy (IOHDR) via a remote afte rloader. Patients and Methods. Patients with Ewing's sarcoma (n = 5), rhabdomyosarcoma (n = 3), synovial cell sarcoma (n = 2), Wilms tumor ( n = 2), osteosarcoma, immature teratoma, desmoplastic small round cell tumor, and inflammatory fibrosclerosis were included. IOHDR was used in the initial management of nine pa tients and at the time of recurre nce in seven. indications for treatment included gross residual diseas e in 5 and suspected microscopic disease in 11. The general sites trea ted were the abdomen (n = 3), chest-wall/thoracic cavity (n = 7), and pelvis (n = 6). All of the patients received multiagent chemotherapy p rior to the IOHDR procedure, and 5 had been previously treated with ex ternal beam radiation therapy. Separate from the procedure during whic h IORT was performed, 9 patients underwent an attempt at resection at the time of their initial presentation. A dose of 1200 cGy was prescri bed to a depth of 0.5 cm from the surface of a multichannel tissue-equ ivalent applicator. Complications ascribedto IOHDR included an abscess , delayed wound healing, and cytopenia. Four patients received supplem ental external beam radiation therapy to the IOHDR site. At the time o f IOHDR, 3 patients had disseminated disease within the pleural cavity and one had pulmonary metastases. Results. With a median follow-up of 18 months, the actuarial rates of local control, metastasis-free, and overall survival at 2 years were 61%, 51%, and 54%, respectively. The patterns of failure were local (n = 1), distant (n = 1), and local distant (n = 1). Two patients are alive with active disease. Nine are alive with no evidence of disease and the remaining 5 are dead from di sease (n = 2), other causes (n = 1), OF treatment (n = 2). Conclusions . The potential to improve local control with high doses of radiation should be balanced against the risk of late effects. The ability to co nfine the dose of radiation to the primary site and decrease the dose to normal tissues makes IOHDR an important adjunct to external beam ra diation therapy. IOHDR can be a safe and integral component in the man agement of pediatric solid tumors. (C) 1998 Wiley-Liss, Inc.