Natural history of early chronic lymphocytic leukemia. A single institution study with emphasis on the impact of disease-progression on overall survival

Abstract

Background and objective: Criteria for identifying patients with early chronic lymphocytic leukemia (CLL) who are likely to progress to a more advanced clinical stage rely on results of prospective clinical trials. Is not clear whether these same criteria apply to patients followed-up in the setting of clinical practice. With the aim of addressing this issue we investigated the clinical outcome of a series of patients with Binet stage A CLL.

Design and methods: Two hundred and four Binet stage A CLL patients observed at a single institution over an 18-year period form the basis of this study. Different proposals for subclassifying Binet stage A were validated by using our patients as test-set cases.

Results: The survival of patients with early CLL (i.e., Binet stage A and Rai stage 0) was significantly different from that of an age- and sex-matched population. Three of 4 different criteria for subclassifying stage A (Rai substaging, Montserrat criteria, French Group proposal), when applied to our patients, gave similar results in terms of sample size, death rate and disease progression (DP) risk. The French Group proposal, based exclusively on blood counts and hemoglobin levels, was not effective in predicting the risk of DP. Forty-nine (23.5%) patients progressed to a more advanced clinical stage (30 to stage B and 19 to stage C); the risk of DP was 32.8% at 5 years and 49.6% at 10 years. When analyzed as a time-dependent variable (Mantel-Byar method), DP had a clear cut-impact on overall survival (p < 0.0001). Finally, outlook for survival of patients who experienced a change of clinical stage was similar to that of patients in that stage at the time of diagnosis.

Interpretation and conclusions: As many patients are now being diagnosed while asymptomatic and at a younger age than previously, an accurate evaluation of prognosis is mandatory in early CLL. How prognostic information translates into a policy of early or delayed therapy is still unclear. Our results further support a conservative approach for CLL in early stage; patients who progress into a more advanced stage have similar survival to those in that stage at diagnosis.