Prospective Registry of ADC as First- and Second-line Treatment for Breast Cancer

This registry is tracking real-world outcomes for people with advanced breast cancer who are receiving a class of drugs called antibody-drug conjugates (ADCs) — targeted medicines that deliver chemotherapy directly to cancer cells. The study aims to understand how well these treatments work and in which patients. **You may be eligible if...** - You are 18 years or older with advanced (metastatic) breast cancer - You have hormone-receptor-positive/HER2-negative breast cancer, or triple-negative breast cancer - You are starting or continuing treatment with an FDA-approved ADC as part of standard care - You are willing to provide tumor tissue and blood samples at several points during the study - Your life expectancy is at least 3 months **You may NOT be eligible if...** - You are not receiving an ADC as part of your current treatment plan - You are unwilling or unable to provide tissue and blood samples Talk to your doctor to see if this trial is right for you.