When cancer begins in one part of the body and spreads to another, it is called metastasis. Brain metastases are when primary lung cancer has produced one or more secondary tumors in the brain.

Lung cancer with brain metastases is a common complication of cancer. Approximately 10% of patients newly diagnosed with advanced non-small cell lung cancer have brain metastases. About 40 to 50% of brain metastases come from lung cancer.