Clinico-biological Characterization and Survival of Patients With Adult T-cell Leukemia / Lymphoma (ATL) and Patients Chronically Infected With the HTLV-1 Virus (HTLV-OBS)

This observational study tracks patients infected with the HTLV-1 virus — a virus that can cause a rare type of blood cancer called adult T-cell leukemia/lymphoma (ATL). Researchers will collect clinical and biological information to better understand how the disease develops and affects survival. **You may be eligible if...** - You are 18 or older - You are infected with the HTLV-1 virus - You either have been diagnosed with ATL-related blood cancer (cohort 1) or are infected but without cancer (cohort 2) - You agree to have your data collected for the study **You may NOT be eligible if...** - You refuse to participate Talk to your doctor to see if this trial is right for you.