ESTRO 2024 - Abstract Book

S1720

Clinical - Lung

ESTRO 2024

compared to 20% in those treated with RFA. Fewer SBRT patients had systemic therapy either preceding or following ablative treatment: 57.1% and 51.4% in the SBRT group vs 72.6% and 68.9% in the RFA group, respectively.

The primary diagnoses being treated with either modality differed significantly. Twenty-four (96%) patients with soft tissue sarcoma (STS) were treated with RFA, while all (13) melanoma patients were treated with SBRT. RFA was favoured in colorectal patients (75%) and SBRT was favoured in RCC and endometrial cancer (77% and 71% respectively). Patients with various primary diagnoses were treated with the commonest being colorectal (84), STS (25), and endometrial cancer (14). Median progression-free survival (PFS) was 12.5 months for SBRT and 7.2 months for RFA. Median OS was 49.9 months for SBRT vs 48.8 months for RFA. In subgroup analysis, SBRT and RFA demonstrated similar PFS in smaller tumours (<=20mm) but SBRT offered better local control in tumours >20mm. RFA offered better local control in colorectal patients (93.5% vs 66.7%). In univariable analysis, lesion size >20mm was statistically significant in predicting adverse local PFS (HR 3.62 (95% CI 1.75-7.51), PFS (HR 1.45 (95% CI 1.02-2.06)) and OS (HR 2.22 (95% CI 1.38-3.58). This remained statistically significant in multivariable analysis in predicting local PFS and OS. Oligometastatic status did not reach statistical significance in univariable analysis.

Conclusion:

This study highlights differences in patient selection and outcomes for RFA or SBRT in the treatment of lung metastases at our institution, with larger lesions more frequently being treated with SBRT, and with SBRT offering better local control than RFA in lesions larger than 20mm. Future studies with larger patient numbers are required to assess individual histological subtypes to determine the optimum treatment modality.

Keywords: SBRT, RFA, Metastatic

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