Efficacy and Failure Patterns of Early SBRT to the Primary Tumor in Advanced EGFR Mutation-Positive Lung Cancer with EFGR-TKI treatment: A Prospective, Single Arm, Phase II Study

Introduction: Early stereotactic body radiation therapy (SBRT) to the primary tumor combined with EFGR-TKI treatment may increase progression-free survive (PFS) by delaying resistance in patients with advanced EGFR-mutant NSCLC. Methods In this prospective, single arm phase II study, patients with advanced NSCLC were treated with EGFR TKI (Icotinib125mg tid or gefitinib 250mg qd) for one month followed by SBRT (40-60Gy/5-8F/5-10d) to the primary tumor with concurrent EGFR TKI until disease progression. The primary endpoint was PFS and the patterns of failure. Overall survival (OS) and adverse effects (AEs) were second endpoints. Results Overall 41 advanced NSCLC patients with EGFR mutations received treatment with 24.42 months of median follow-up time. On average, SBRT was initiated 1.49 months after EGFR-TKI administration. Tumors were found to have an average shrinkage rate of 42.50%. Median PFS was 15.23 months (95% CI 13.10-17.36), while median OS was 27.57 months (95% CI 23.05–32.09). Thirty-three patients were found to have disease progression, of which new site failure (NF) (22 patients, 66.66%) was the most common pattern, followed by original site failure (OF) (7 patients, 21.21%) and Simultaneous OF/NF (ONF) (4 patients, 12.12%). There was no AEs equal to or greater than grade 3 with the most frequent AE being radiation pneumonitis. Conclusions Administering therapy targeted at the primary tumor using early SBRT after EGFR-TKI initiation is a new potential safe and effective approach to treat EGFR-mutant advanced NSCLC.