Intraoperative RT (IORT)

Local control for pediatric solid tumors, such as rhabdomyosarcoma, often requires high doses of EBRT, which can cause unwanted damage to the normal tissues surrounding the tumor. After maximal tumor resection, delivering some or all of the radiation dose to the sites of highest recurrence risk intraoperatively could mitigate this issue, especially in relapsed patients who have received previous EBRT or very young children. This procedure is called intraoperative radiation therapy (IORT), and it can be used in challenging cases where standard full-dose EBRT is contraindicated. During IORT, a single large dose of radiation is administered during surgical exploration with direct visualization of the tumor bed and radiation field. IORT has been deemed safe to use for malignancies in pediatric patients, with minimal long-term toxicities.[50]

A single-institution retrospective study examined IORT (108 applications) in 96 pediatric patients with solid tumors (42 with rhabdomyosarcoma) who were treated from 1995 to 2022. The median age at time of IORT was 8 years (range, 0.8–20.9 years). The median follow-up was 16 months for all patients and 3 years for surviving patients. About one-half of patients (54%) were treated with upfront IORT to the primary tumor because of difficult circumstances, such as very young age or challenging anatomy. The median IORT dose was 12 Gy (range, 4–18 Gy). The cumulative incidence rate of local failure was 17% at 2 years and 23% at 5 years. A total of 15 patients (16%) experienced postoperative complications likely related to IORT.[51]

While IORT may be advantageous in the treatment of certain high-risk patients, there are important disadvantages. IORT is only available at certain institutions. In addition, while IORT minimizes the radiation dose to surrounding tissues by delivering one large fraction, any healthy tissue that is exposed is at risk of long-term treatment effects later in life.[51]