2177 - Interstitial Brachytherapy for Soft Tissue Sarcomas: Outcomes and Patterns of Failure Patterns from a Single Institution Experience

02:30pm - 04:00pm PT

Hall F

Screen: 33

POSTER

Presenter(s)

Romy Megahed, MD - UAMS Radiation Oncology, Little Rock, AR

R. J. Megahed¹, P. Sabouri¹, F. Kalantari¹, J. S. Cordova¹, C. Montgomery², and R. L. Crownover¹; ¹Department of Radiation Oncology, University of Arkansas for Medical Sciences, Little Rock, AR, ²Department of Orthopedic Surgery, University of Arkansas for Medical Sciences, Little Rock, AR

Purpose/Objective(s): Soft tissue sarcomas represent a heterogeneous group of malignancies with a significant risk of local recurrence following surgery. While external beam radiation therapy has been the standard adjuvant modality, interstitial brachytherapy (IBT), which delivers a highly conformal radiation dose directly to the tumor bed while sparing surrounding healthy tissue, has emerged as an effective alternative. Several studies have demonstrated favorable local control with IBT but data on post-surgical outcomes in patients receiving high-dose rate (HDR) IBT remains limited. This study evaluates clinical outcomes, including locoregional control, distant metastasis, and treatment-related complications, in patients undergoing surgery followed by HDR IBT radiation for soft tissue sarcomas.

Materials/Methods: Between February 2021 and December 2023, 15 adults patients (age range: 30-89, median 55 years) with a diagnosis of soft tissue sarcoma underwent surgical resection followed by HDR IBT with an iridium-192 source. Brachytherapy was initiated between postoperative days 2 to 10 (median 4 days).

All but two patients received a prescribed dose of 36 Gy in 10 fractions, delivered twice daily (BID). One patient with prior radiation therapy received 32 Gy in 10 fractions BID, while another patient underwent 35.1 Gy in 9 fractions BID due to logistical constraints. Tumor grading was classified as follows: grade 1 (n=0), grade 2 (n=4), and grade 3 (n=11).

Results: The median follow-up duration was 24.4 months (range: 3.1 -36.8 months). Locoregional recurrence was observed in 1 of 15 patients (6.7%), while 5 of 15 patients (33.3%) developed distant metastases. The median time to distant metastasis was 4.2 months (range: 1-17 months). The overall survival (OS) rate was 73.3% at last follow-up. Postoperative complications included perioperative surgical site infections in 3 of 15 patients (20%), all of which were successfully managed with oral antibiotics. Additionally, 2 of 15 patients (13.3%) experienced delayed wound healing or chronic wound complications. Seven radiation oncology residents participated in at least one interstitial implant.

Conclusion: Postoperative HDR IBT demonstrates excellent locoregional control in patients with soft tissue sarcoma, with a low incidence of perioperative complications. Our findings support HDR IBT as an effective, safe, and well-tolerated adjuvant treatment modality, offering precise and convenient approach to delivering targeted radiation while minimizing toxicity.