Differentiating chronic lymphocytic leukemia from monoclonal B-lymphocytosis according to clinical outcome: on behalf of the GIMEMA chronic lymphoproliferative diseases working group

Abstract

Background Optimal lymphocyte parameters and thresholds for the diagnosis of chronic lymphocytic leukemia have been proposed by The National Cancer Institute sponsored Working Group and recently updated by the International Workshop on chronic lymphocytic leukemia. However, it is not clear how these criteria apply to patient management in daily clinical practice and whether the lymphocyte thresholds recommended truly predict clinical outcome in early chronic lymphocytic leukemia.Design and Methods For the purpose of this study, an observational database of the GIMEMA (Gruppo Italiano Malattie Ematologiche dell’Adulto) which included 1,158 patients with newly diagnosed Binet stage A chronic lymphocytic leukemia who were observed at different primary hematology centers during the period 1991–2000, was used.Results Among 818 consecutive chronic lymphocytic leukemia patients with Rai stage 0 (i.e. no palpable lymphadenopathy or hepatosplenomegaly) who had flow cytometry evaluations at the time of diagnosis and were included in a GIMEMA database, both absolute lymphocyte count and B-cell count were of a similar value in predicting time to first treatment as continuous variables (P<0.0001). Receiver operating characteristic analysis identified an absolute lymphocyte count of 11.5×109/L and an absolute B-cell count of 10.0×109/L as the best thresholds capable of identifying patients who will require treatment from those with stable disease. However, in a Cox’s multivariate analysis only the B-cell count retained its discriminating power (P