Retrospective and Prospective Observational Study in Patients With Advanced Basal Cell Carcinoma

This observational study collects real-world data on patients with advanced basal cell carcinoma (a type of skin cancer) — including those whose cancer has grown too large for surgery or radiation, or whose cancer has spread to lymph nodes or distant organs. The goal is to better understand outcomes and treatment patterns in clinical practice. **You may be eligible if...** - You are 18 years or older - You have been diagnosed with advanced basal cell carcinoma (locally advanced, meaning it cannot be fully removed by surgery or radiation, OR metastatic, meaning it has spread to lymph nodes or other organs) - You have had at least one visit (initial or follow-up) at a participating dermatology or oncology clinic **You may NOT be eligible if...** - You are unable to give informed consent Talk to your doctor to see if this trial is right for you.