Treatment Outcomes after Pulmonary Stereotactic Body Radiotherapy for Oligometastatic or Oligorecurrent Lung Lesions

Abstract

Abstract Objective Using ablative techniques like stereotactic body radiation therapy (SBRT) in patients with limited metastases may improve survival outcomes in select groups of patients. We review the outcomes of patients treated with oligometastatic/recurrent lung lesions in our centre and analyse variables that might have affected them. Methods A retrospective review of patients treated from Jan 2010 to Dec 2016 was conducted. The data was analysed using SPSS ver23. Results A total of 46 patients with 51 lung lesions were treated with SBRT. Majority of lesions were of lung and colorectal cancers. Histological confirmation was obtained in 50%. Median SBRT biological effective dose (BED) was 105.6Gy and median follow-up was 26.9 months. There were 12 (22.6%) local failures at last follow-up. Median progression free survival (PFS) was 13.7 months (95% CI: 3.9 -23.5 months). Median overall survival (OS) was 42.2 months (95% CI: 30.8 - 53.5 months). The 2 year PFS and OS was 32.6% and 81.9% respectively. There were 3 (6.5%) likely radiotherapy related grade 3-4 pulmonary toxicities. On univariate analysis, local control rates were better with a higher BED and in squamous cell histology. Progression free survival was better for patients with metachronous lesions, higher BED, controlled primary lesions and when treatment to all visible lesions was given. Only patients with solitary metastatic lesions had better OS (44.7 months) and PFS (21.9 months) on univariate analysis. Local failure and progression predicted for worst OS. Conclusion The patients in this study are heterogeneous. Survival outcomes were better in patients with solitary metastatic lesions. This may be due to selection of patients with indolent disease biology. Better PFS were seen with higher BED and when all visible lesions were ablated. Further studies are needed.