Hairy cell leukemia is a highly treatable disease. Since it is easily controlled, many patients have prolonged survival with sequential therapies. The decision to treat is based on cytopenias (especially if symptomatic), increasing splenomegaly, indications that the disease is progressing, or the presence of other, usually infectious complications. It is reasonable to offer no therapy if the patient is asymptomatic, and blood counts are maintained in an acceptable range.
Purpose of This Summary
This PDQ cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about treatment of plasma cell neoplasms (including multiple myeloma). It is intended as a resource to inform and assist clinicians who care for cancer patients. It does not provide formal guidelines or recommendations for making health care decisions.
Reviewers and Updates
This summary is reviewed regularly and updated as necessary...
Cladribine (2-chlorodeoxyadenosine, 2-CdA) given intravenously by continuous infusion, by daily subcutaneous injections, or by 2-hour infusions daily for 5 to 7 days, results in a complete response rate of 50% to 80% and an overall response rate of 85% to 95%.[1,2,3,4,5,6,7] The response rate was lower in 979 patients treated with the Group C mechanism of the National Cancer Institute (i.e., 50% complete remission rate, 37% partial remission rate). Responses are durable with this short course of therapy, and patients who relapse often respond to retreatment with cladribine.[8,9,10] This drug may cause fever and immunosuppression with documented infection in 33% of treated patients. In a retrospective study of patients with cladribine-associated neutropenic fever, filgrastim (G-CSF) did not demonstrate a decrease in the percentage of febrile patients, number of febrile days, or frequency of admissions for antibiotics. (Refer to the PDQ summary on Fever, Sweats, and Hot Flashes for more infformation on fever.) A potential increased risk for second malignancies with this agent remains controversial.
Pentostatin given intravenously every other week for 3 to 6 months produces a 50% to 76% complete response rate and an 80% to 87% overall response rate.[12,13] Complete remissions are of substantial duration. In two trials with 9-year median follow-up, relapse-free survival ranged from 56% to 67%.[14,15] Side effects include fever, immunosuppression, cytopenias, and renal dysfunction. (Refer to the PDQ summary on Fever, Sweats, and Hot Flashes for information on fever.) A randomized comparison of pentostatin and interferon-alpha demonstrated higher and more durable responses to pentostatin.
Interferon-alpha given subcutaneously 3 times per week for 1 year yields a 10% complete response rate and an 80% overall response rate. The drug frequently produces an influenza-like syndrome early in the course of treatment. Late effects include depression and lethargy. (Refer to the PDQ summary on Depression and for more information on lethargy, refer to the the PDQ summary on Fatigue.) Responding patients who relapse usually respond to retreatment with interferon-alpha. Remission can be prolonged with a low-dose maintenance regimen. A randomized comparison of pentostatin and interferon-alpha demonstrated significantly higher and more durable responses to pentostatin.
Splenectomy will partially or completely normalize the peripheral blood in the vast majority of patients with hairy cell leukemia. Usually little or no change occurs in the bone marrow after splenectomy, and virtually all patients have progressive disease within 12 to 18 months. Therefore, since a number of more effective alternatives are available, splenectomy is playing a decreasing role in the treatment of this disease.