Excellent local control and survival after intraoperative and external beam radiotherapy for pediatric solid tumors: long-term follow-up of the Mayo Clinic experience

Use of external beam radiotherapy (EBRT) for pediatric solid malignancies is generally limited by the tolerance of normal tissue in developing organs. Intraoperative electron radiotherapy (IOERT) allows a more focal delivery of radiation dose because vital organs can be displaced and avoided during treatment. From February 1983 to July 2003, 20 children underwent IOERT for treatment of locally advanced or recurrent malignancies of the extremity or abdominopelvic area. All patients underwent EBRT and received IOERT doses of 7.5 to 25 Gy with 6-MeV to 15-MeV electrons. At a median follow-up of 11.6 years (range, 2.1 to 25.5 y), 13 patients (65%) were alive and without evidence of disease. Patients who underwent gross total resection had better local control (88% vs. 67%) and survival (71% vs. 33%) than patients for whom the resection was not achieved. Among 7 patients, 11 grade 3 toxicity events were reported. No grade >3 toxicities or second malignancies were observed during follow-up. Use of IOERT in combination with surgery and EBRT in management of pediatric solid malignancies provides excellent local control with reasonable toxicity. IOERT should be considered as an integral part of a multimodality regimen for pediatric solid malignancies, especially for patients with abdominopelvic malignancies.