Abstract
To investigate whether imaging features from pretreatment planning CT scans are associated with overall survival (OS), recurrence-free survival (RFS), and loco-regional recurrence-free survival (LR-RFS) after stereotactic body radiotherapy (SBRT) among nonsmall-cell lung cancer (NSCLC) patients. A total of 92 patients (median age: 73yr) with stage I or IIA NSCLC were qualified for this study. A total dose of 50Gy in five fractions was the standard treatment. Besides clinical characteristics, 24 "semantic" image features were manually scored based on a point scale (up to 5) and 219 computer-derived "radiomic" features were extracted based on whole tumor segmentation. Statistical analysis was performed using Cox proportional hazards model and Harrell's C-index, and the robustness of final prognostic model was assessed using tenfold cross validation by dichotomizing patients according to the survival or recurrence status at 24months. Two-year OS, RFS and LR-RFS were 69.95%, 41.3%, and 51.85%, respectively. There was an improvement of Harrell's C-index when adding imaging features to a clinical model. The model for OS contained the Eastern Cooperative Oncology Group (ECOG) performance status [Hazard Ratio (HR)=2.78, 95% Confidence Interval (CI): 1.37-5.65], pleural retraction (HR=0.27, 95% CI: 0.08-0.92), F2 (short axis×longest diameter, HR=1.72, 95% CI: 1.21-2.44) and F186 (Hist-Energy-L1, HR=1.27, 95% CI: 1.00-1.61); The prognostic model for RFS contained vessel attachment (HR=2.13, 95% CI: 1.24-3.64) and F2 (HR=1.69, 95% CI: 1.33-2.15); and the model for LR-RFS contained the ECOG performance status (HR=2.01, 95% CI: 1.12-3.60) and F2 (HR=1.67, 95% CI: 1.29-2.18). Imaging features derived from planning CT demonstrate prognostic value for recurrence following SBRT treatment, and might be helpful in patient stratification.
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