The results of phase III FLAURA study showed a significant PFS benefit for first-line Osimertinib versus standard EGFR-TKIs in patients with EGFR mutation-positive NSCLC, the median PFS was 18.9 months and 10.2 months, respectively. However, only 136 Chinese patients were enrolled in FLAURA study. The objectives of this study are to assess the efficacy and safety of Osimertinib in a real world setting in Chinese patients with locally advanced or metastatic, treatment naïve, epidermal growth factor receptor (EGFR) mutation-positive Non-Small Cell Lung Cancer (NSCLC).

Total of ~30 study sites are selected for conducting this observational study. Eligible patients will be prospectively and consecutively included. Therefore, the clinical practice in the selected patients group can represent the "real-world" situation in China, and the patient's medical record will be well documented and archived in those hospitals. All data defined in the protocol will be collected during the study and entered in the Electric Data Capture (EDC), being consistent to the patients' medical records.

The most important bias of the study is that patients' characteristics will affect the treatment duration, efficacy and safety, such as, higher proportion of patients with WHO PS 2~3 enroll in the study will result in shorter TTD, poorer effectiveness and higher toxicities than expected. The ~30 sites are not randomly selected and potential selection bias exists. To minimize enrolment bias, the patients who are eligible and consent to participate in the current study will be enrolled consecutively as per protocol and without personal preference from investigators.

The self-selection bias may exit for the willingness and non-willingness participants. We'll try our best to discuss with the non-willingness participants to make sure the consistency/comparative between the willingness and non-willingness participants.

There could be a certain percentage of patients who would lost to follow up, it is unavoidable in clinical study, and is more common in real world study. We can minimize the bias by selecting the hospitals with normative and high-quality clinical practice, trying to collect the reason of lost to follow up and enhancing patient management during the follow up. The above bias is acceptable as this is a "real-world" study. Only descriptive analysis will be performed for the primary, secondary and exploratory objectives. No statistical comparisons between subgroups will be done.

Inclusion Criteria:

• Ability to provide informed consent, complete all study assessments and have complete medical record;
• Histologically or cytologically documented locally advanced, metastatic NSCLC, which are not amenable to curative surgery or radiotherapy;
• With confirmation of the presence of the EGFR mutation.
• Patients must be treatment- naïve for locally advanced or metastatic NSCLC.
• Age ≥ 18 years
• Patients who plan to receive Osimertinib monotherapy as the initial first line treatment based on physician's medical judgement.

Exclusion Criteria:

• Patients who will be or were involved in any other interventional anti-tumour clinical studies for locally advanced/metastatic NSCLC currently or previously
• Any concomitant condition evaluated by physicians which is not suitable for Osimertinib treatment.
• Patients who have received the first dose of Osimertinib before the signature of ICF won't be allowed to enroll in.

The patients with locally advanced/metastatic, EGFR mutation-positive NSCLC who are intent to be prescribed Osimertinib as the first line treatment are eligible to be the study target population.

Base on the current clinical practice, it is estimated that the brain scans could be performed to approximately 350 patients at the baseline, approximately 200 patients' tissue or blood sample could be available at the baseline for de novo T790M analysis, and few patients with uncommon EGFR mutation, and/or patients with PS 2-3 could be included base on the current CSCO lung cancer guideline and clinical practice.