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NCI/PDQ^® Health professionals: Hairy Cell Leukemia Treatment (PDQ®)

National Cancer Institute
Last Modified: July 16, 2012

TABLE OF CONTENTS

• General Information About Hairy Cell Leukemia

• Stage Information for Hairy Cell Leukemia

• Treatment Option Overview

• Treatment for Hairy Cell Leukemia
  • Untreated Hairy Cell Leukemia
  • Progressive Hairy Cell Leukemia
  • Current Clinical Trials

• Relapsed or Refractory Hairy Cell Leukemia
  • Current Clinical Trials

• Changes to This Summary (07/16/2012)

• About This PDQ® Summary
  • Purpose of This Summary
  • Reviewers and Updates
  • Levels of Evidence
  • Permission to Use This Summary
  • Disclaimer
  • Contact Us

• Get More Information From NCI

General Information About Hairy Cell Leukemia

Hairy cell leukemia is a chronic lymphoproliferative disorder that is easily controlled. The decision to treat is based on symptomatic cytopenias, massive splenomegaly, or the presence of other complications. About 10% of all patients will never require therapy.

Stage Information for Hairy Cell Leukemia

No generally accepted staging system is useful for both prognosis and therapy.

For the purpose of treatment decisions, it is best to consider this disease in the following two broad categories:

• Untreated hairy cell leukemia.
• Progressive hairy cell leukemia, either postsplenectomy or postsystemic therapy.

Untreated hairy cell leukemia

Untreated hairy cell leukemia is characterized by splenomegaly, varying degrees of leukopenia (occasionally leukocytosis) and/or pancytopenia, and bone marrow infiltration by an atypical cell with prominent cytoplasmic projections (i.e., hairy cells). The bone marrow is usually fibrotic and is not easily aspirated. Bone marrow biopsies are, therefore, required for diagnosis and evaluation of the degree of hairy cell infiltration.

Progressive hairy cell leukemia

Progressive hairy cell leukemia, postsplenectomy (or following any systemic therapy) is characterized by progressive bone marrow replacement by hairy cells with pancytopenia refractory to treatment. For patients with advanced hairy cell leukemia treated with cladribine (2-chlorodeoxyadenosine, 2-CdA), pentostatin, or interferon-alpha, the survival rate appears to be more than 85% at 5 years following the initiation of any one of these therapies. 1 2

References:

1. Frassoldati A, Lamparelli T, Federico M, et al.: Hairy cell leukemia: a clinical review based on 725 cases of the Italian Cooperative Group (ICGHCL). Italian Cooperative Group for Hairy Cell Leukemia. Leuk Lymphoma 13 (3-4): 307-16, 1994. [PUBMED Abstract]
2. Kurzrock R, Strom SS, Estey E, et al.: Second cancer risk in hairy cell leukemia: analysis of 350 patients. J Clin Oncol 15 (5): 1803-10, 1997. [PUBMED Abstract]

Treatment Option Overview

The initial therapies of choice are either cladribine (2-chlorodeoxyadenosine, 2-CdA) or pentostatin. 1 2 These drugs have comparable response rates but have not been compared in phase III trials. Cladribine is administered as a one-time continuous infusion or series of subcutaneous injections and is associated with a high rate of febrile neutropenia. 3 4 5 6 Rarely, more than one course of treatment is required to induce a desirable response. Treatment should be discontinued once complete remission or stable partial remission with normalization of peripheral blood counts is reached. The presence of residual disease may be predictive of relapse but does not seem to affect survival. 5 7

The role of consolidation or maintenance therapy in preventing relapse or progression of the disease following treatment with purine analogs has not been evaluated and remains unproven. Pentostatin is administered intermittently for a longer treatment duration but may result in a lower incidence of febrile complications. 8 9 While most patients remain disease free 10 years after treatment with these purine analogs, no patient has been followed long enough to assess cure. 10 11 Both nucleoside analogs cause profound suppression of CD4 counts, which may last for a year, and a potential increased risk of second malignancies has been reported. 5 12

A study of 3,104 survivors of hairy cell leukemia from the SEER database showed an increased risk of second cancers (standardized incidence ratio = 1.24; 95% CI, 1.111.37), especially for Hodgkin and non-Hodgkin lymphomas. 13 The increased risk for second cancers was seen even in the 2 decades prior to the introduction of purine nucleosides. 13 With the use of cladribine, an increased risk of second malignancies is possible among patients with hairy cell leukemia (observed to expected ratio of about 1.8 in several series after 6 years). 5 12 Several series using pentostatin did not report an increased risk of second malignancies. 8 10 14 For a few patients, such as those with severe thrombocytopenia, splenectomy might be considered. 15 After splenectomy, 50% of patients will require no additional therapy, and long-term survivors are common. Therapy with interferon-alpha is another treatment option, especially for patients with intercurrent infection. 9 16

Hairy cell leukemia variant has a distinctive phenotype and typically presents with leukocytosis instead of leukopenia. 17 These patients have poorer responses to initial cladribine, shorter durations of response, and typically do not respond again to purine analogues after relapse. Combinations of rituximab and purine analogues are under evaluation and further studies are required to define optimal therapies. 18 19

References:

1. Gidron A, Tallman MS: 2-CdA in the treatment of hairy cell leukemia: a review of long-term follow-up. Leuk Lymphoma 47 (11): 2301-7, 2006. [PUBMED Abstract]
2. Grever MR, Lozanski G: Modern strategies for hairy cell leukemia. J Clin Oncol 29 (5): 583-90, 2011. [PUBMED Abstract]
3. Hoffman MA, Janson D, Rose E, et al.: Treatment of hairy-cell leukemia with cladribine: response, toxicity, and long-term follow-up. J Clin Oncol 15 (3): 1138-42, 1997. [PUBMED Abstract]
4. Cheson BD, Sorensen JM, Vena DA, et al.: Treatment of hairy cell leukemia with 2-chlorodeoxyadenosine via the Group C protocol mechanism of the National Cancer Institute: a report of 979 patients. J Clin Oncol 16 (9): 3007-15, 1998. [PUBMED Abstract]
5. Goodman GR, Burian C, Koziol JA, et al.: Extended follow-up of patients with hairy cell leukemia after treatment with cladribine. J Clin Oncol 21 (5): 891-6, 2003. [PUBMED Abstract]
6. Jehn U, Bartl R, Dietzfelbinger H, et al.: An update: 12-year follow-up of patients with hairy cell leukemia following treatment with 2-chlorodeoxyadenosine. Leukemia 18 (9): 1476-81, 2004. [PUBMED Abstract]
7. Fayad L, Kurzrock R, Keating M, et al.: Treatment of hairy-cell leukemia (HCL) with 2-CdA: long term follow-up at M.D. Anderson Cancer Center. Blood 90(suppl 1): A2363, 1997. [PUBMED Abstract]
8. Ribeiro P, Bouaffia F, Peaud PY, et al.: Long term outcome of patients with hairy cell leukemia treated with pentostatin. Cancer 85 (1): 65-71, 1999. [PUBMED Abstract]
9. Grever M, Kopecky K, Foucar MK, et al.: Randomized comparison of pentostatin versus interferon alfa-2a in previously untreated patients with hairy cell leukemia: an intergroup study. J Clin Oncol 13 (4): 974-82, 1995. [PUBMED Abstract]
10. Flinn IW, Kopecky KJ, Foucar MK, et al.: Long-term follow-up of remission duration, mortality, and second malignancies in hairy cell leukemia patients treated with pentostatin. Blood 96 (9): 2981-6, 2000. [PUBMED Abstract]
11. Chadha P, Rademaker AW, Mendiratta P, et al.: Treatment of hairy cell leukemia with 2-chlorodeoxyadenosine (2-CdA): long-term follow-up of the Northwestern University experience. Blood 106 (1): 241-6, 2005. [PUBMED Abstract]
12. Au WY, Klasa RJ, Gallagher R, et al.: Second malignancies in patients with hairy cell leukemia in british columbia: a 20-year experience. Blood 92 (4): 1160-4, 1998. [PUBMED Abstract]
13. Hisada M, Chen BE, Jaffe ES, et al.: Second cancer incidence and cause-specific mortality among 3104 patients with hairy cell leukemia: a population-based study. J Natl Cancer Inst 99 (3): 215-22, 2007. [PUBMED Abstract]
14. Kurzrock R, Strom SS, Estey E, et al.: Second cancer risk in hairy cell leukemia: analysis of 350 patients. J Clin Oncol 15 (5): 1803-10, 1997. [PUBMED Abstract]
15. Golomb HM, Vardiman JW: Response to splenectomy in 65 patients with hairy cell leukemia: an evaluation of spleen weight and bone marrow involvement. Blood 61 (2): 349-52, 1983. [PUBMED Abstract]
16. Capnist G, Federico M, Chisesi T, et al.: Long term results of interferon treatment in hairy cell leukemia. Italian Cooperative Group of Hairy Cell Leukemia (ICGHCL). Leuk Lymphoma 14 (5-6): 457-64, 1994. [PUBMED Abstract]
17. Matutes E, Wotherspoon A, Catovsky D: The variant form of hairy-cell leukaemia. Best Pract Res Clin Haematol 16 (1): 41-56, 2003. [PUBMED Abstract]
18. Else M, Osuji N, Forconi F, et al.: The role of rituximab in combination with pentostatin or cladribine for the treatment of recurrent/refractory hairy cell leukemia. Cancer 110 (10): 2240-7, 2007. [PUBMED Abstract]
19. Arons E, Suntum T, Stetler-Stevenson M, et al.: VH4-34+ hairy cell leukemia, a new variant with poor prognosis despite standard therapy. Blood 114 (21): 4687-95, 2009. [PUBMED Abstract]

Treatment for Hairy Cell Leukemia

Untreated Hairy Cell Leukemia

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. 1

Progressive Hairy Cell Leukemia

Standard treatment options:

1. 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). 3 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. 3 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. 11 (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.
2. 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. 12
3. 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. 16 Remission can be prolonged with a low-dose maintenance regimen. 17 A randomized comparison of pentostatin and interferon-alpha demonstrated significantly higher and more durable responses to pentostatin. 12
4. Splenectomy will partially or completely normalize the peripheral blood in the vast majority of patients with hairy cell leukemia. 18 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.

Trials (including NCT00923013) are ongoing studying combinations of cladribine plus the monoclonal antibody rituximab.

Current Clinical Trials

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with untreated hairy cell leukemia and progressive hairy cell leukemia, initial treatment. The list of clinical trials can be further narrowed by location, drug, intervention, and other criteria.

General information about clinical trials is also available from the NCI Web site.

References:

1. Gidron A, Tallman MS: 2-CdA in the treatment of hairy cell leukemia: a review of long-term follow-up. Leuk Lymphoma 47 (11): 2301-7, 2006. [PUBMED Abstract]
2. Hoffman MA, Janson D, Rose E, et al.: Treatment of hairy-cell leukemia with cladribine: response, toxicity, and long-term follow-up. J Clin Oncol 15 (3): 1138-42, 1997. [PUBMED Abstract]
3. Cheson BD, Sorensen JM, Vena DA, et al.: Treatment of hairy cell leukemia with 2-chlorodeoxyadenosine via the Group C protocol mechanism of the National Cancer Institute: a report of 979 patients. J Clin Oncol 16 (9): 3007-15, 1998. [PUBMED Abstract]
4. Goodman GR, Burian C, Koziol JA, et al.: Extended follow-up of patients with hairy cell leukemia after treatment with cladribine. J Clin Oncol 21 (5): 891-6, 2003. [PUBMED Abstract]
5. Robak T, Basiska-Morawiec M, Krykowski E, et al.: 2-chlorodeoxyadenosine (2-CdA) in 2-hour versus 24-hour intravenous infusion in the treatment of patients with hairy cell leukemia. Leuk Lymphoma 22 (1-2): 107-11, 1996. [PUBMED Abstract]
6. Robak T, Jamroziak K, Gora-Tybor J, et al.: Cladribine in a weekly versus daily schedule for untreated active hairy cell leukemia: final report from the Polish Adult Leukemia Group (PALG) of a prospective, randomized, multicenter trial. Blood 109 (9): 3672-5, 2007. [PUBMED Abstract]
7. Zenhíusern R, Schmitz SF, Solenthaler M, et al.: Randomized trial of daily versus weekly administration of 2-chlorodeoxyadenosine in patients with hairy cell leukemia: a multicenter phase III trial (SAKK 32/98). Leuk Lymphoma 50 (9): 1501-11, 2009. [PUBMED Abstract]
8. Jehn U, Bartl R, Dietzfelbinger H, et al.: An update: 12-year follow-up of patients with hairy cell leukemia following treatment with 2-chlorodeoxyadenosine. Leukemia 18 (9): 1476-81, 2004. [PUBMED Abstract]
9. Chadha P, Rademaker AW, Mendiratta P, et al.: Treatment of hairy cell leukemia with 2-chlorodeoxyadenosine (2-CdA): long-term follow-up of the Northwestern University experience. Blood 106 (1): 241-6, 2005. [PUBMED Abstract]
10. Else M, Dearden CE, Matutes E, et al.: Long-term follow-up of 233 patients with hairy cell leukaemia, treated initially with pentostatin or cladribine, at a median of 16 years from diagnosis. Br J Haematol 145 (6): 733-40, 2009. [PUBMED Abstract]
11. Saven A, Burian C, Adusumalli J, et al.: Filgrastim for cladribine-induced neutropenic fever in patients with hairy cell leukemia. Blood 93 (8): 2471-7, 1999. [PUBMED Abstract]
12. Grever M, Kopecky K, Foucar MK, et al.: Randomized comparison of pentostatin versus interferon alfa-2a in previously untreated patients with hairy cell leukemia: an intergroup study. J Clin Oncol 13 (4): 974-82, 1995. [PUBMED Abstract]
13. Ribeiro P, Bouaffia F, Peaud PY, et al.: Long term outcome of patients with hairy cell leukemia treated with pentostatin. Cancer 85 (1): 65-71, 1999. [PUBMED Abstract]
14. Johnston JB, Eisenhauer E, Wainman N, et al.: Long-term outcome following treatment of hairy cell leukemia with pentostatin (Nipent): a National Cancer Institute of Canada study. Semin Oncol 27 (2 Suppl 5): 32-6, 2000. [PUBMED Abstract]
15. Flinn IW, Kopecky KJ, Foucar MK, et al.: Long-term follow-up of remission duration, mortality, and second malignancies in hairy cell leukemia patients treated with pentostatin. Blood 96 (9): 2981-6, 2000. [PUBMED Abstract]
16. Golomb HM, Ratain MJ, Fefer A, et al.: Randomized study of the duration of treatment with interferon alfa-2B in patients with hairy cell leukemia. J Natl Cancer Inst 80 (5): 369-73, 1988. [PUBMED Abstract]
17. Capnist G, Federico M, Chisesi T, et al.: Long term results of interferon treatment in hairy cell leukemia. Italian Cooperative Group of Hairy Cell Leukemia (ICGHCL). Leuk Lymphoma 14 (5-6): 457-64, 1994. [PUBMED Abstract]
18. Golomb HM, Vardiman JW: Response to splenectomy in 65 patients with hairy cell leukemia: an evaluation of spleen weight and bone marrow involvement. Blood 61 (2): 349-52, 1983. [PUBMED Abstract]

Relapsed or Refractory Hairy Cell Leukemia

Cladribine (2-chlorodeoxyadenosine, 2-CdA) and pentostatin are both highly efficacious in the treatment of patients with disease refractory to interferon-alpha. 1 2 3 4 Patients who relapse after the first course of cladribine or pentostatin often respond well to retreatment with the same or another purine analog. 5 6 7 8 9 10 Rituximab can induce durable complete remissions with minimal toxic effects in patients with multiple relapsing or refractory disease after purine analog therapy or after interferon. 11 12 13 14[Level of evidence: 3iiiDiv] The lack of subsequent immunosuppression with rituximab has made this treatment a common choice among relapsing patients in the absence of a clinical trial. 13 Combinations of rituximab with either cladribine or pentostatin are effective in achieving complete remission and are under clinical evaluation. 10 15 16 Both anti-CD25 and anti-CD22 recombinant immunotoxins under clinical evaluation can induce complete remissions in patients whose disease is resistant to retreatment with purine analogs or rituximab. 17 18

Trials (including the ongoing NCT00923013, NCT00321555, and CAT-8015-1001 [NCT00462189] studies, and NCI-04-C-0014, which is now completed) are in the process of evaluating, or have evaluated, new therapies for this group of patients.

Aggressive, high-dose chemotherapy has been beneficial in some cases, but the associated morbidity and mortality are high. It should not be considered unless other, more frequently effective therapies have been exhausted.

Current Clinical Trials

Check for U.S. clinical trials from NCI's list of cancer clinical trials that are now accepting patients with refractory hairy cell leukemia. The list of clinical trials can be further narrowed by location, drug, intervention, and other criteria.

General information about clinical trials is also available from the NCI Web site.

References:

1. Piro LD, Carrera CJ, Carson DA, et al.: Lasting remissions in hairy-cell leukemia induced by a single infusion of 2-chlorodeoxyadenosine. N Engl J Med 322 (16): 1117-21, 1990. [PUBMED Abstract]
2. Tallman MS, Hakimian D, Variakojis D, et al.: A single cycle of 2-chlorodeoxyadenosine results in complete remission in the majority of patients with hairy cell leukemia. Blood 80 (9): 2203-9, 1992. [PUBMED Abstract]
3. Saven A, Burian C, Koziol JA, et al.: Long-term follow-up of patients with hairy cell leukemia after cladribine treatment. Blood 92 (6): 1918-26, 1998. [PUBMED Abstract]
4. Grever M, Kopecky K, Foucar MK, et al.: Randomized comparison of pentostatin versus interferon alfa-2a in previously untreated patients with hairy cell leukemia: an intergroup study. J Clin Oncol 13 (4): 974-82, 1995. [PUBMED Abstract]
5. Hoffman MA, Janson D, Rose E, et al.: Treatment of hairy-cell leukemia with cladribine: response, toxicity, and long-term follow-up. J Clin Oncol 15 (3): 1138-42, 1997. [PUBMED Abstract]
6. Goodman GR, Burian C, Koziol JA, et al.: Extended follow-up of patients with hairy cell leukemia after treatment with cladribine. J Clin Oncol 21 (5): 891-6, 2003. [PUBMED Abstract]
7. Ribeiro P, Bouaffia F, Peaud PY, et al.: Long term outcome of patients with hairy cell leukemia treated with pentostatin. Cancer 85 (1): 65-71, 1999. [PUBMED Abstract]
8. Zinzani PL, Magagnoli M, Bendandi M, et al.: Long-term follow-up of hairy cell leukemia patients treated with 2-chlorodeoxyadenosine. Haematologica 85 (9): 922-5, 2000. [PUBMED Abstract]
9. Gidron A, Tallman MS: 2-CdA in the treatment of hairy cell leukemia: a review of long-term follow-up. Leuk Lymphoma 47 (11): 2301-7, 2006. [PUBMED Abstract]
10. Else M, Dearden CE, Matutes E, et al.: Long-term follow-up of 233 patients with hairy cell leukaemia, treated initially with pentostatin or cladribine, at a median of 16 years from diagnosis. Br J Haematol 145 (6): 733-40, 2009. [PUBMED Abstract]
11. Hagberg H, Lundholm L: Rituximab, a chimaeric anti-CD20 monoclonal antibody, in the treatment of hairy cell leukaemia. Br J Haematol 115 (3): 609-11, 2001. [PUBMED Abstract]
12. Lauria F, Lenoci M, Annino L, et al.: Efficacy of anti-CD20 monoclonal antibodies (Mabthera) in patients with progressed hairy cell leukemia. Haematologica 86 (10): 1046-50, 2001. [PUBMED Abstract]
13. Thomas DA, O'Brien S, Bueso-Ramos C, et al.: Rituximab in relapsed or refractory hairy cell leukemia. Blood 102 (12): 3906-11, 2003. [PUBMED Abstract]
14. Angelopoulou MK, Pangalis GA, Sachanas S, et al.: Outcome and toxicity in relapsed hairy cell leukemia patients treated with rituximab. Leuk Lymphoma 49 (9): 1817-20, 2008. [PUBMED Abstract]
15. Ravandi F, Jorgensen JL, O'Brien SM, et al.: Eradication of minimal residual disease in hairy cell leukemia. Blood 107 (12): 4658-62, 2006. [PUBMED Abstract]
16. Else M, Osuji N, Forconi F, et al.: The role of rituximab in combination with pentostatin or cladribine for the treatment of recurrent/refractory hairy cell leukemia. Cancer 110 (10): 2240-7, 2007. [PUBMED Abstract]
17. Kreitman RJ, Wilson WH, White JD, et al.: Phase I trial of recombinant immunotoxin anti-Tac(Fv)-PE38 (LMB-2) in patients with hematologic malignancies. J Clin Oncol 18 (8): 1622-36, 2000. [PUBMED Abstract]
18. Kreitman RJ, Stetler-Stevenson M, Margulies I, et al.: Phase II trial of recombinant immunotoxin RFB4(dsFv)-PE38 (BL22) in patients with hairy cell leukemia. J Clin Oncol 27 (18): 2983-90, 2009. [PUBMED Abstract]

Changes to This Summary (07/16/2012)

The PDQ® cancer information summaries are reviewed regularly and updated as new information becomes available. This section describes the latest changes made to this summary as of the date above.

Editorial changes were made to this summary.

This summary is written and maintained by the PDQ® Adult Treatment Editorial Board, which is editorially independent of NCI. The summary reflects an independent review of the literature and does not represent a policy statement of NCI or NIH. More information about summary policies and the role of the PDQ® Editorial Boards in maintaining the PDQ® summaries can be found on the About This PDQ® Summary and PDQ® NCI's Comprehensive Cancer Database pages.

About This PDQ® Summary

Purpose of This Summary

This PDQ® cancer information summary for health professionals provides comprehensive, peer-reviewed, evidence-based information about the treatment of hairy cell leukemia. 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 by the PDQ® Adult Treatment Editorial Board, which is editorially independent of the National Cancer Institute (NCI). The summary reflects an independent review of the literature and does not represent a policy statement of NCI or the National Institutes of Health (NIH).

Board members review recently published articles each month to determine whether an article should:

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Changes to the summaries are made through a consensus process in which Board members evaluate the strength of the evidence in the published articles and determine how the article should be included in the summary.

The lead reviewers for Hairy Cell Leukemia Treatment are:

• Steven D. Gore, MD (Johns Hopkins University)
• Mark J. Levis, MD, PhD (Johns Hopkins University)
• Eric J. Seifter, MD (Johns Hopkins University)
• Mikkael A. Sekeres, MD, MS (Cleveland Clinic Taussig Cancer Institute)

Any comments or questions about the summary content should be submitted to Cancer.gov through the Web site's Contact Form. Do not contact the individual Board Members with questions or comments about the summaries. Board members will not respond to individual inquiries.

Levels of Evidence

Some of the reference citations in this summary are accompanied by a level-of-evidence designation. These designations are intended to help readers assess the strength of the evidence supporting the use of specific interventions or approaches. The PDQ® Adult Treatment Editorial Board uses a formal evidence ranking system in developing its level-of-evidence designations.

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National Cancer Institute: PDQ® Hairy Cell Leukemia Treatment. Bethesda, MD: National Cancer Institute. Date last modified . Available at: http://cancer.gov/cancertopics/pdq/treatment/hairy-cell-leukemia/HealthProfessional. Accessed .

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