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Published on: May 8, 2018
Partially Ablative Body Radiation Therapy Versus Standard Palliative Radiation Therapy for Locally Advanced Bulky
Christopher Williams1,2, Julie Chu3,4, SuChen Fong3
1Faculty of Medicine, The University of Queensland, St Lucia, Australia.
Purpose:
Locally advanced soft tissue sarcomas cause significant tumor mass effects, often leading to onerous symptoms. Our institution has previously developed partially ablative body radiation therapy (PABR) for palliation in these circumstances, which has demonstrated effective symptom relief. However, these outcomes have not been compared with clinical outcomes from standard palliative radiation therapy (SPR).
Methods And Materials:
A total of 57 patients (30 PABR and 27 SPR) with various soft tissue sarcomas >5 cm in diameter treated between December 2019 and April 2024 were retrospectively reviewed. The primary endpoints were symptomatic and objective structural response rates and were compared using binomial regression. Secondary endpoints were overall survival, freedom from local progression, and freedom from distant progression.
Results:
The median age was 73 years and 56 years in the PABR and SPR groups, respectively. The median tumor volume was 898.55 cm3 and 205 cm3, respectively. The predominant dose and fractionation were 20 Gy in 5 fractions with an intratumoral boost to 50 Gy (90.0%) in the PABR group, while 30 Gy in 10 fractions (48.1%) was most common in the SPR group. After a median follow-up of 9 months, 90% of patients in the PABR group experienced symptomatic improvement compared with 70% in the SPR group. In multivariate analysis, PABR was associated with significantly higher rates of symptomatic improvement (adjusted relative risk, 1.30; 95% CI, 1.03-1.63; P = .026). Regarding objective response, 73.3% versus 48.2% of patients exhibited a partial response, with stable disease observed in 13.3% versus 11.1% of patients in the PABR and SPR groups, respectively. Mean absolute tumor volume reduction was 38% versus 35%. One-year estimated overall survival was 57.4% (95% CI, 35.6%-74.2%) versus 40.7% (95% CI, 22.5%-58.2%), freedom from local progression was 69.7% (95% CI, 43.2%-85.6%) versus 33.1% (95% CI, 15.0%-52.6%), and freedom from distant progression was 46.8% (95% CI, 23.4%-67.2%) versus 3.7% (95% CI, 0.3%-15.9%) for the PABR and SPR groups, respectively.
Conclusions:
PABR for bulky unresectable sarcomas may provide improved palliation of symptoms compared to SPR, with potentially better local control despite treating significantly larger tumors.
