Intraoperative Radiation Therapy for Pediatric Patients: A 25 Year Experience

Abstract

To assess outcomes after intra-operative radiation therapy (IORT) in pediatric patients, including local control, overall survival, and toxicity. Single institution retrospective study of 184 pediatric patients treated with IORT from 1995-2022. Each IORT application was considered a separate event for a total of 213 sites treated. Local failure was calculated using the cumulative incidence function and survival by Kaplan-Meier method from the day of surgery. Median follow up for all patients was 14 months while median follow up for surviving patients was 3 years. Median patient age was 6 years (range 9 months to 21 years) and half were male. Patients were generally high risk with 76% having relapsed or refractory disease. Tumor types included neuroblastoma (n = 88), soft tissue sarcoma (n = 69), Wilms tumor (n = 11), and other solid tumors (n = 24). The majority (97%) of patients had prior chemotherapy, 69% had at least one prior attempt at resection, and 65% had prior external beam radiation to the site of IORT. Location of IORT included the retroperitoneum (n = 99), anterior abdominal wall (n = 14), pelvic region (n = 49), chest and thorax (n = 36), head (n = 5), neck (n = 7), and axilla/shoulder (n = 3), with a median dose of 12 Gy (range 4 to 18 Gy). Overall survival was 47% and 32% at 2 and 5 years respectively. Rates of local failure were 20% and 26% at 2 and 5 years. Local failure had a significant impact on overall survival (p = 0.009). Analyzing specific tumor types at 2 years, the rate of local failure and overall survival were 22% and 57% for soft tissue sarcomas, 23% and 39% for neuroblastoma, and 10% and 60% for Wilms tumor. Direct toxicity from IORT was rare, however there were several cases of surgical complications where a potential contribution from IORT could not be ruled out. The most common complications included abscesses in the surgical field, fistula or stricture development, and hydronephrosis. There were no post-operative mortalities related to IORT. Our study represents the largest scale analysis of efficacy and safety of IORT in patients with pediatric solid tumors. Less than one third of patients failed locally at 5 years. Achieving local control impacted overall survival, emphasizing the importance of local control in these patients. Minimal radiation related toxicities were observed. Overall, IORT is an effective technique to achieve local control in children with high-risk solid tumors.