Prognostic factors in chronic lymphocytic leukemia.

The Rai staging system is widely used and is easy to apply in clinical practice. The system introduced by Binet et al offers an advantage that it consists only of three stages and, therefore, is more practical for initiation of controlled therapeutic trials than the five-stage Rai system. However, when we take into consideration the survival curves, it is important to note that the Rai system has three groups (and not five), low risk (stage O), intermediate risk (stages I and II), and high risk (stages III and IV). These groups are roughly equivalent to Binet's A, B, and C stages, respectively. Although the IWCLL has recommended a unified, integrated method of combining Binet and Rai systems, in practice, however, such a combination is cumbersome and unusable. Both systems, however, suffer from an important limitation--they cannot predict for the large majority of patients in the low and intermediate risk groups (Binet's stages A and B and Rai's O, I, and II) who will have an indolent course and good prognosis in contrast to those in the same stages whose disease will progress rapidly. It is necessary, therefore, to combine the bone marrow histology findings, the lymphocyte doubling time and the threshold values of blood lymphocyte count with the clinical staging systems to distinguish between indolent disease course and aggressive disease on a prospective basis within a given clinical stage.