Background
Locally advanced sarcomas cause significant tumour mass effects, leading to burdensome symptoms. Peter MacCallum Cancer Institute has previously developed Partially Ablative Body Radiotherapy (PABR) for palliation that has shown effective relief of symptoms. These outcomes however, have not been compared with clinical outcomes from standard palliative radiotherapy (SPR).
Aims
This study aims to report the comparative clinical outcomes of PABR versus SPR in patients with bulky, unresectable sarcomas.
Methods
A total of 54 patients: 27 PABR and 27 SPR, with sarcoma treated from December 2019 to April 2024 were retrospectively reviewed. The primary endpoints were symptomatic and objective structural response rates. Secondary endpoints were overall survival (OS), freedom from local progression (FFLP) and freedom from distant progression (FFDP).
Results
All patients had tumours >5cm with a median tumour volume of 898 cc and 205 cc in the PABR and SPR groups. The median age was 75.5 years and 56 years respectively. The most common dose and fractionation was 20Gy in 5 fractions with an intratumoral boost to 50Gy (92.6%) in the PABR group and 30gy in 10 fractions (48.1%) in the SPR group. After a median follow up of 9.5 months, 77.8% versus 48.1% patients exhibited a partial response to treatment, with a mean absolute tumour volume reduction of 46% v 30% in the PABR and SPR groups respectively. All patients in the PABR group had an improvement in symptoms while 77.8% in the SPR group had an improvement. One year estimated OS was 59% (95% CI 43-93) versus 40% (95% CI 26-64), FFLP was 76.3% (95% CI 60-98) versus 33.1% (95% CI 18-60) and FFDP was 44.3% (95% CI 25-78) versus 3.7% (95% CI 0.5-25) for the PABR and SPR groups respectively.
Conclusion
PABR for bulky unresectable sarcomas may provide greater palliation of symptoms then standard palliative radiotherapy.