Radiomics Based Prediction of Local Recurrence Following Stereotactic Body Radiation Therapy (SBRT) for Early-Stage Non-Small Cell Lung Cancer

Stereotactic body radiation therapy (SBRT) represents an effective therapeutic strategy for early-stage non-small cell lung cancer (NSCLC), however local and systemic recurrences represent ongoing challenges. Computed tomography (CT) radiomics based risk models can potentially be utilized to predict the risk of local recurrence on pre-treatment CT scans. This single institution study includes a retrospective case-control training set (20 patients with local recurrence and 40 controls) and an independent validation set (198 consecutive cases) of early-stage NSCLC patients treated with SBRT. Tumors were semi-automatically segmented and 102 quantitative radiomic features including texture, landscape, spatial, nodule shape, and nodule surface features extracted. These features were included in three separate multivariable models to predict the risk of recurrence based on the pre-SBRT, post-SBRT, and the difference between the pre-SBRT and the post-SBRT scans (Delta model). The pre-SBRT model was subsequently validated in an independent validation set. Thirteen independent variables were selected for the models using the Boruta algorithm. The sensitivity, specificity, and area under the curve (AUC) of the pre-SBRT, post-SBRT and Delta-models were 85%, 90%, and 0.91; 85%, 92.5%, and 0.92; and 85%, 92.5%, and 0.94, respectively. The pre-SBRT model was validated in the independent validation set, AUC of 0.89 (CI 0.83-0.92) as this model was felt to be the most useful to assist in individualized treatment planning. Radiomic analysis facilitated the development of three high-performing models predicting local recurrence using either pre-SBRT CT, post-SBRT CT, or the change between these two. We successfully validated the most clinically relevant model, pre-SBRT model. While this model needs further validation, it may facilitate individualized surveillance, treatment planning and selection of adjuvant therapy.