The role of radiotherapy in multimodal treatment of non-rhabdomyosarcoma soft tissue sarcomas in children: A real life report from a tertiary center.

Objective: The current treatment of pediatric non-rhabdomyosarcoma soft tissue sarcomas (NRSTS) is a multimodal risk-based approach. Today, smaller fields and lower doses of radiotherapy (RT) have become standard. In this study, it was aimed to evaluate the treatment outcomes and toxicity profile in children with NRSTS that received RT as a part of multimodal therapy.

Methods: Twenty-nine patients with pediatric NRSTS treated with neoadjuvant or adjuvant RT between 1998 and 2022 were evaluated retrospectively. Kaplan-Meier method was used for survival analyses.

Results: Median follow-up was 36 months (range, 6-291 months). The median neoadjuvant and adjuvant RT doses were 50 Gy (range, 45-66 Gy) and 54 Gy (45-66 Gy), respectively. During follow-up, six (21%) patients developed a local recurrence and 10 (35%) had distant metastasis. The 5-year local control, overall survival (OS), local recurrence-free survival, and distant metastasis-free survival rate was 79%, 67%, 59%, and 61%, respectively. In multivariate analysis, a ≤5-cm tumor, gross tumor resection, Children's Oncology Group (COG) low-risk group, and absence of neoadjuvant chemotherapy were independent favorable prognostic factors for OS. Severe (≥ grade 3) late toxicity was observed in 6 (20%) patients.

Conclusions: RT is a crucial component in the multimodal risk-based treatment approach for pediatric NRSTS. However, late toxicity rates are still high and should be improved. Patients with a ≤5-cm tumor, COG low-risk group and treated with gross tumor resection have increased survival rates.