This is a multi-center observational study with both retrospective and prospective data collections to describe the effectiveness and safety of sequential dacomitinib and 3rd generation EGFR-TKI used in patients with EGFR mutation-positive NSCLC with T790M-aquired resistance in a clinical practice setting. The study will include patients who were or will be diagnosed as advanced NSCLC with EGFR mutation positive and received dacomitinib as first-line treatment followed by second-line 3rd generation EGFR-TKI treatment in multiple tertiary care hospitals after Sep 1st, 2019. Patients' clinical information prior to the study initiation in each hospital will be collected retrospectively through chart review. After the study initiation, new patient enrollment will last till Dec 2022. Patients' clinical care after the study initiation will be followed up prospectively until the end of study. The interval of response evaluation is recommended to be every 2 to 3 months in the treatment period and the interval of follow-up is recommended to be every 2 to 3 months in the post-treatment period till the end of study in the prospective data collection period.
