Understanding Chronic Lymphocytic Leukemia

This is an observational study that collects information and samples from patients with chronic lymphocytic leukemia (CLL) — a slow-growing blood cancer — and related conditions, to help researchers better understand how these diseases develop and respond to treatment over time. **You may be eligible if...** - You have been diagnosed with chronic lymphocytic leukemia (CLL), monoclonal B-cell lymphocytosis (a precursor condition), or another low-grade lymphoproliferative disorder (a slow-growing blood cell condition) - You are seen for treatment at Dana-Farber Cancer Institute or elsewhere **You may NOT be eligible if...** - There are no formal exclusion criteria listed for this study Talk to your doctor to see if this trial is right for you.