*2.2. Response Evaluation*

Best clinical response to treatment with TKI was classified on the basis of interval CT scans as complete response (CR), partial response (PR), stable disease (SD), or progressive disease (PD) using standard Response Evaluation Criteria in Solid Tumors criteria (RECIST) version 1.1. Patients with both baseline imaging and at least one repeated evaluation after continuous *EGFR*-TKI monotherapy were evaluable for radiographic response. The same criteria for response evaluation and periodicity were used by all centers taking part in the study.
