In-depth feasibility study on conservative surgery, perioperative high-dose-rate brachytherapy, and external beam radiation therapy, with a focus on interstitial brachytherapy for soft tissue sarcomas: Insights from a single-institute experience

Purpose: Soft tissue sarcomas (STS) due to their aggressive nature, pose challenges in achieving optimal local control (LC) rates following surgery. Brachytherapy offers precise delivery of high radiation doses to target tissues, potentially enhancing LC rates. This feasibility study explored the efficacy of perioperative high-dose-rate brachytherapy (PHDRB) and external beam radiation therapy (EBRT) in improving LC rates for STS, with a particular focus on interstitial brachytherapy and dose escalation strategies for high-risk patient sub-groups.

Material and methods: Seven patients with STS underwent conservative surgery and PHDRB between October 2020 and October 2023. PHDRB doses ranged from 3.0 to 3.5 Gy BID in 10 fractions, with or without subsequent EBRT, as indicated. EBRT was delivered in 4-5 weeks after surgical procedure at a dose of 45-50 Gy in 25 treatments, with daily dose of 1.8-2.0 Gy. Brachytherapy techniques and dosimetry guidelines were meticulously implemented to ensure optimal treatment delivery and minimize toxicity.

Results: All seven patients tolerated treatment well without acute or late radiation-related complications. Excellent local disease control was achieved in all cases, but three patients developed distant metastases. The overall feasibility and efficacy of PHDRB in combination with EBRT were promising.

Conclusions: This study underscores the feasibility and potential efficacy of PHDRB and EBRT for STS treatment. Despite limitations in sample size, the results are promising, warranting further investigation through multi-centric studies. The use of dose-escalated PHDRB in high-risk cases enabled more intensive treatment delivery directly to the tumor bed, which may be critical for enhancing local control in patients with aggressive or large tumors. In facilities with limited resources and a high patient burden, where conformal radiotherapy is unavailable, brachytherapy remains an excellent modality for boosting the tumor bed or serving as a radical radiotherapy treatment.