To evaluate disease control and survival after stereotactic body radiotherapy (SBRT) for lung metastases from colorectal cancer and to identify prognostic factors after treatment.
Patients with metastatic colorectal cancer to the lungs treated with SBRT from 2002 to 2013 were identified from a prospectively maintained database. Patients may have received prior systemic therapy, radiotherapy to nonthoracic sites and/or resection of thoracic and/or nonthoracic metastases. Endpoints were timed from end of SBRT and included overall survival (OS), progression-free survival, distant metastases-free survival, and local failure-free survival. Univariate and multivariate analysis using Cox proportional hazard modeling was used to identify prognostic factors.
Sixty-five patients were identified. Before SBRT, 69.2% and 33.8% of patients received systemic therapy and lung-directed local therapy, respectively, for metastatic disease. At the time of SBRT, 64.6% had lung-only involvement. Median survivals were: OS of 20.3 months (95% confidence intervals [CI], 15.9-27.0 mo), progression-free survival of 5.7 months (95% CI, 3.2-7.0 mo), distant metastases-free survival of 5.8 months (95% CI, 3.2-7.6 mo), and local failure-free survival of 15.4 months (95% CI, 8.5-21.1 mo). Nearly all (98%) patients developed distant progression. Extra lung and liver involvement at the time of initial metastases (hazard ratios [HR] 2.10) and extra lung involvement at SBRT (HR 2.67) were the only independent predictors of OS. Net gross target volume of >14.1 mL (HR 2.49) was the only independent predictor of local failure-free survival.
Reasonable survival and local control can be achieved with SBRT. We identified several prognostic factors testable in future prospective trials that may help improve patient selection.
*Wilmot Cancer Institute, University of Rochester
†University of Rochester School of Medicine
¶Department of Radiation Oncology, University of Rochester Medical Center, Rochester, NY
∥University of Florida Health, Cancer Center University of Florida, Gainesville, FL
‡Radiation Oncology Associates P.A., Manchester, NH; and
§Dayton Physicians Network, Dayton, OH
The authors declare no conflicts of interest.
Reprints: Michael T. Milano, MD, PhD, Wilmot Cancer Institute, University of Rochester, 601 Elmwood Avenue, Box 647, Rochester, NY 14642. E-mail: firstname.lastname@example.org.