Study on Stereotactic Radiosurgery and Standard Treatment for Lung Cancer Spread to the Brain

Inclusion Criteria

• Must be 18 years or older.
• Have non-small cell lung cancer (NSCLC) with a specific EGFR mutation confirmed by the study center.
• Have at least one brain metastasis that is 1 cm or larger, visible on scans before starting osimertinib.
• Either have not started osimertinib or have started it within the last 3 months, with records of the start date and scans before starting the medication.

Exclusion Criteria

• Cannot undergo an MRI with contrast.
• Have had previous radiation treatment to the brain.
• Have signs of cancer in the brain's protective layers (leptomeningeal disease) on MRI or spinal fluid tests, if done.
• Have neurological symptoms or brain lesions needing immediate SRS treatment.
• Have active blood cancers or another type of cancer known to spread to the brain.
• Have had surgery to remove brain metastases unless there are still untreated brain metastases that meet size criteria.
• Are judged by the study doctor as unlikely to follow study procedures.
• Are pregnant, breastfeeding, or able to become pregnant without using effective birth control during the study and for 3 months after the last treatment.

Randomization Inclusion Criteria:

• Have detectable and stable brain metastases on scans, showing remaining disease.

Randomization Exclusion Criteria:

• Have worsening disease with multiple lesions needing a change in treatment.
• Have brain metastases that cannot be safely treated with SRS.
• Have no visible brain metastases (complete response).
• Have more than 20 visible brain metastases after initial treatment with osimertinib, although there is no limit on the number of metastases before starting osimertinib.