An Observational Study of Local Relapse After High Grade Osteosarcoma

This observational study collects data on patients with high-grade osteosarcoma (a type of bone cancer) whose cancer came back in the same location after treatment, in order to better understand what happens and what affects survival. **You may be eligible if...** - You had localized high-grade bone osteosarcoma and your cancer came back in the same location (local relapse) as the first sign of recurrence - You are able to attend follow-up visits - You are willing to provide written consent - There is no age limit **You may NOT be eligible if...** - Your local relapse happened more than 3 months after cancer had already spread to other sites - You are unable to reliably attend follow-up visits Talk to your doctor to see if this trial is right for you.