Efficacy of Palliative SBRT in Local Control of Sarcoma

Objective For patients presenting with recurrent, inoperable, or metastatic sarcoma, treatment options are limited. The inherent low radiosensitivity of many sarcoma histologies can limit effectiveness of palliative radiation for these patients. Stereotactic radiation (SBRT) allows escalation of biologically effective dose while limiting dose to normal tissues, which is particularly important in previously irradiated tissues. In this retrospective cohort study, we examine the efficacy of SBRT in the palliation of sarcoma. Methods A retrospective cohort study was performed of patients treated at a single large tertiary academic medical center with SBRT for management of sarcoma from 2011 through 2016. Details regarding patient demographics, treatment context, tumor histology, treatment parameters, and disease outcomes were recorded. Descriptive statistics and Cox analysis of factors associated with improved local control were examined. Results Results were available on 22 tumors treated with SBRT in 14 patients. Median follow-up was 6.7 months. Median tumor size was 4.8 cm, with a median total dose and dose per fraction of 27.5 Gy and 6 Gy/fraction, respectively. There were 6 recurrences, with a 1-year local control of 62%. Seventy-nine percent of symptomatic lesions had improvement in their pain. On univariate Cox-analysis, total dose, performance status, and BMI were found to be significantly associated with local control, and dose per fraction was significantly associated with local failure. One-year overall survival was 37%. Conclusion Our institutional experience provides encouraging evidence of the feasibility of SBRT in the palliation of sarcoma. Poor overall survival is a substantial competing risk in these patients. Further studies will be required to identify the ideal dose and fractionation across histological subtypes. Prospective clinical trials may be warranted.