To evaluate disease control and survival after stereotactic body radiation therapy (SBRT) for lung metastases from colorectal cancer (CRC) and identify prognostic factors after treatment. Materials/Methods: Sixty-five patients with metastatic CRC to the lungs treated with SBRT from 2002-2013 were identified from a prospectively maintained database. Patients may have received prior systemic therapy, radiation therapy to non-thoracic sites and resection of thoracic and/or non-thoracic metastases. The endpoints were overall survival (OS), progression-free survival (PFS), distant metastases free survival (DMFS) and local failure free survival (LFFS). Univariate and multivariate analysis using Cox proportional hazard modeling was used to identify prognostic factors. Results: Prior to SBRT, 69.2% and 55.4% of patients received systemic therapy and local therapy respectively for metastatic disease. At the time of SBRT, 64.6% had only lung involvement. Most (81.6%) patients received a dose of >70 Gy BED. Median OS, PFS, DMFS, and LFFS were 20.4 months (M), 5.7 M, 5.8 M, and 15.4 M respectively. Nearly all (98%) patients had distant failure as a component of disease progression. Extra lung and liver involvement at the time of initial metastases (HR 2.10) and extra lung involvement at SBRT (HR 2.67) were independent predictors of OS. ECOG performance of !2 (HR 3.01), male gender (HR 2.94), interval between diagnosis and metastatic presentation 2 years (HR 2.25) and extra lung involvement at time SBRT (HR 2.52) were independently associated with increased risk of disease progression. Net GTV volume >14.1cc (HR 2.50) was the only independent predictors of LFFS. Conclusion: Reasonable survival and local control can be achieved with SBRT. We identified several prognostic factors testable in future prospective trials that may help to improve patient selection.
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