Temporal evolution of CT imaging features in oligometastatic lung lesions after stereotactic body radiation therapy: a multicenter retrospective study of early tumor response as a predictor of favorable local control

Background: Stereotactic body radiation therapy (SBRT) is an effective treatment for pulmonary oligometastases. Understanding the temporal evolution of computed tomography (CT) imaging features post-SBRT is crucial for optimizing patient management and improving prognostic outcomes. This study aimed to characterize the CT imaging evolution of pulmonary oligometastatic nodules following SBRT and evaluate the prognostic value of early tumor response for local control. Methods: This multicenter retrospective study analyzed 246 pulmonary oligometastatic nodules in 191 patients treated with SBRT. We evaluated clinical characteristics, biologically effective dose (BED10), and CT imaging features, categorized by recurrence within 2 years. Tumor response at 1-month follow-up was classified as favorable [partial response (PR) or complete response (CR)] or bad [stable disease (SD) or progressive disease (PD)]. Statistical analyses included t-tests, Chi-squared tests, and Kaplan-Meier analysis. Results: Significant predictors of non-recurrence included tumor diameter ≤20 mm (P