To the Editor: Crespo et al. (May 1 issue)1 present informativedata on ZAP-70 as a surrogate prognostic marker for chroniclymphocytic leukemia (CLL). The patients in their study hadheterogeneous backgrounds and may have been treated by differenttreatment strategies according to their age and disease status.Elderly patients with advanced or refractory CLL may have receivedless intensive treatment than others, leading to a poorer prognosis.Because treatments differ greatly in their effects on overallsurvival, there may have been a selection bias in the study.The authors have not provided sufficient information on thesevariables. Clinicians will appreciate it if the authors canshare the data on treatments.
Naoko Murashige, M.D. Masahiro Kami, M.D. Yoichi Takaue, M.D. National Cancer Center Hospital Tokyo 104-0045, Japan mkami{at}ncc.go.jp
References
Crespo M, Bosch F, Villamor N, et al. ZAP-70 expression as a surrogate for immunoglobulin-variable-region mutations in chronic lymphocytic leukemia. N Engl J Med 2003;348:1764-1775. [Free Full Text]
The authors reply: Murashige et al. make interesting commentsconcerning the clinical characteristics and treatment of thepatients in our study. At our institution, patients in whomBinet stage A CLL is diagnosed do not receive therapy unlessthey meet criteria for active CLL.1 Treatment has, of course,varied over the years, from chlorambucil to fludarabine-basedcombination regimens. Interestingly, in our series, only 3 ofthe 18 patients with Binet stage A disease and low ZAP-70 expressionrequired treatment, whereas 20 of the 26 patients with highZAP-70 expression were treated. The main clinical variables,including age, did not differ between the two groups. Thus,with ZAP-70 analysis we were able to identify a group of patientswith a bad prognosis, irrespective of the clinical stage. Finally,the relation among ZAP-70 expression, clinical variables, andsurvival should be assessed in larger series of patients.
The source of the monoclonal anti–ZAP-70 antibody usedfor flow cytometry was Upstate Biotechnology.
Cheson BD, Bennett JM, Grever M, et al. National Cancer Institute-sponsored Working Group guidelines for chronic lymphocytic leukemia: revised guidelines for diagnosis and treatment. Blood 1996;87:4990-4997. [Free Full Text]
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