Assessment of Disease Burden in Hairy Cell Leukemia

This study is looking at the burden of disease in people with hairy cell leukemia — a rare, slow-growing blood cancer — at different stages: newly diagnosed, in relapse, or in remission. Researchers want to better understand treatment needs and long-term outcomes. **You may be eligible if...** - You are 18 or older - You have a confirmed diagnosis of hairy cell leukemia - You are newly diagnosed and about to start treatment, OR in relapse needing further therapy, OR in remission for at least 5 years **You may NOT be eligible if...** - You have a second active cancer at the same time Talk to your doctor to see if this trial is right for you.