Study in Patients With Breast Cancer Leptomeningeal Metastasis

This study collects data from breast cancer patients who have developed leptomeningeal metastasis — when cancer spreads to the fluid and membranes surrounding the brain and spinal cord. It aims to better understand this serious complication and improve how it is managed. **You may be eligible if...** - You are 18 or older with a history of breast cancer (any type) - You are suspected to have breast cancer that has spread to the leptomeninges (the membranes around the brain/spine), based on symptoms, imaging, or spinal fluid testing - You have an ECOG score of 3 or below, or a Karnofsky score of 60 or above (meaning you can perform at least some self-care) **You may NOT be eligible if...** - Your suspected brain/spine involvement is due to a blood cancer, lymphoma, or a different solid tumor - You are not eligible for leptomeningeal disease treatment Talk to your doctor to see if this trial is right for you.