Perioperative Radiation with/without High Dose Rate Brachytherapy for High-risk Soft Tissue Sarcoma
PO-0257
Abstract
Perioperative Radiation with/without High Dose Rate Brachytherapy for High-risk Soft Tissue Sarcoma
Authors: James Assif1, William Ennis2, Rishabh Chaudhari3, Benjamin Kim4, Stephanie Rice4, Anna Shapiro4, Timothy Damron5, Sean Tanny4, Alexander Banashkevich4, Jeffrey Bogart4
1University of Maryland, Radiation Oncology, Baltimore, USA; 2University of Alabama, Radiation Oncology, Birmingham, USA; 3University of Cincinnati, Radiation Oncology, Cincinnati, USA; 4SUNY Upstate Medical University, Radiation Oncology, Syracuse, USA; 5SUNY Upstate Medical University, Surgery, Syracuse, USA
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Purpose or Objective
Evaluation of the therapeutic ratio of maximal perioperative radiation therapy (MRT = external beam radiotherapy with interstitial high dose rate brachytherapy boost) versus standard radiation therapy (SRT) in the form of external beam radiation therapy (EBRT) in patients with high risk soft tissue sarcomas (STS).
Material and Methods
Retrospective review of STS patients treated between 2009 and 2017 with definitive perioperative radiotherapy with or without interstitial brachytherapy boost. Multidisciplinary evaluation was used to select the highest risk patients for MRT. Chi-square analysis was used to compare MRT and SRT groups, Kaplan-Meier estimates were used for survival and control analysis, and logistic regression was used to evaluate factors predictive of brachytherapy use in our cohort.
Results
Fifty eight patients were identified, 23 (40%) treated with MRT and 35 (60%) SRT. The majority (59%) had grade 3 disease, and 91% had close or positive surgical margins. Median tumor size was 10.5 cm for patients treated with MRT and 6.2 cm for patients treated with SRT. Median brachytherapy dose was 13.5 Gy in 3 fractions over 2 days. After median follow up of 39 months, local control was similar (83%) with MRT and SRT, and no significant difference was observed in distant failure (35% MRT vs 29% SRT, p=0.62). Grade 3+ acute toxicity was higher with MRT, 11 (48%) vs 2 (6%) (p<0.01), respectively, including 16% (n=9) requiring surgical management. There was no significant difference in grade 3+ chronic toxicity between cohorts, 2 (9%) vs 0 (0%) (p=0.39), and no Grade 5 toxicities.
Conclusion
Adding interstitial brachytherapy boost to perioperative external beam radiotherapy for patients with STS did not result in excessive chronic toxicities compared with EBRT alone. Local control was similar with MRT and SRT despite selection of patients with larger tumors in the MRT cohort. The overall impact of interstitial brachytherapy warrants prospective evaluation.