Long-term follow-up studies in hairy cell leukemia.

Enormous progress has been made in the management of patients with hairy cell leukemia (HCL) over the past 50 years since this disease was initially described in 1958. The introduction of the two commonly used purine nucleoside analogs (pentostatin and cladribine, respectively) has independently changed the natural history of this rare malignancy. Both agents are equivalent in terms of response and long-term results. Advances in therapy are being further pursued with inclusion of monoclonal antibodies (e.g. rituximab) and other immunotherapeutic approaches. Patients with this disease now can live a near normal life expectancy, but the disease has not yet been cured. Clinical trials must continue to address the remaining unanswered questions.