Circulating Biomarkers Repository in Adults Diagnosed With Primary and Metastatic Brain Tumors

This study is collecting blood samples from adults with primary brain tumors or cancers that have spread to the brain (brain metastases). Researchers will look for biological markers — small signals in the blood — that could one day be used to diagnose or monitor brain tumors without invasive procedures. **You may be eligible if...** - You are an adult with a confirmed diagnosis of a primary brain tumor or a cancer that has spread to the brain (either confirmed by biopsy/pathology or by imaging) **You may NOT be eligible if...** - There are no specific exclusion criteria listed for this study Talk to your doctor to see if this trial is right for you.