Improving Survival for Metastatic Lobular Breast Cancer (PLUMB Registry)

This study (the PLUMB Registry) is collecting real-world data on patients with metastatic lobular breast cancer — a type of breast cancer that spreads in a different pattern than most breast cancers and can be harder to detect and treat. The goal is to better understand how this cancer behaves and which treatments work best. **You may be eligible if...** - You have confirmed invasive lobular breast cancer (mixed lobular/ductal is also allowed) - Your cancer has spread to other parts of the body (stage IV / metastatic) - You are 18 or older - You are willing and able to give informed consent **You may NOT be eligible if...** - Your cancer is early-stage (stage I–III) and has not spread - Your tumor biopsy does not confirm lobular histology - You have another active cancer at the same time (prior treated cancers with no current evidence of disease are generally allowed) Talk to your doctor to see if this trial is right for you.