This prospective, single-arm, multicenter observational study is designed to estimate the median progression-free survival (PFS) in patients with EGFR-mutant advanced non-small cell lung cancer (NSCLC) who receive salvage local treatment after achieving disease control with first-line osimertinib plus chemotherapy. A total of 70 patients will be enrolled. The primary endpoint is median PFS, and the sample size was calculated to ensure that the 95% confidence interval around the estimated median has a width of no more than ±3 months, using Greenwood's approximation. Patients will be followed for a minimum of 24 months after the last enrollment, with an overall study duration of up to 72 months.
