A Study of Stereotactic Radiosurgery (SRS) and Standard Treatment in People With Lung Cancer That Has Spread to the Brain

The researchers are doing this study is to find out whether treating brain metastasis with SRS after 3 months of therapy with osimertinib is better than treating with osimertinib alone in people with NSCLC. The researchers will also look at how the study intervention impacts participants' quality of life. The researchers will measure quality of life by having participants complete questionnaires.