Confirmation and improvement of Sokal's prognostic classification of Ph+ chronic myeloid leukemia: The value of early evaluation of the course of the disease

Abstract

A simple prognostic classification of Ph + chronic myeloid leukemia (CML) was proposed in 1984 by an international study Group [23] and is now widely used for clinical purposes. That study was retrospective, and was based on disease features at diagnosis. To test prospectively and to check the value of the classification, and to investigate if additional information on the early course of leukemia can help in refining the prognosis, 505 Ph+, nonblastic and nontransplanted patients first registered between 1984 and 1986 were followed up to June 1990. It was found that the prognostic formulation predicted survival in that series exactly the same way as in the original series (median survival: > 60 months for low-risk patients, 46 months for intermediate-risk patients, and 32 months for high-risk ones). It was also found that several objective or subjective assessments of disease course during the first 8 months after diagnosis were significantly related to survival length within any risk group. This study provides full confirmation of Sokal's international prognostic classification, and shows that the definition of prognosis can be improved some months after diagnosis by taking into account the course of the disease and the response to therapy. These conclusions apply to patients receiving conventional treatment. The course of Ph+ chronic myeloid leukemia (CML) is rigidly programmed to progress to an acute phase, which is called blastic metamorphosis (BM) and which can develop either suddenly (blastic crisis) or by a slow progression (accelerated phase) [7,24,29]. In all recent series, 2-year survival ranged between 65% and 80%, median survival was slightly shorter than 4 years, and the proportion of patients who were still alive after 10 years was less than 10% [24,29]. However, a number of prognostic variables were identified [2,8,9,12,15,16,19,23, 28] and a prognostic formulation that was elaborated by an international study [23] was shown to provide a reliable estimate of survival length and is currently used for that purpose. The value of that formulation, and the formulation itself, require periodical controls and revisions. For that purpose, the Italian Cooperative Study Group on CML registered and followed up all CML patients who were first seen between 1984 and 1986. A very preliminary analysis of that cohort of patients has already been performed, but it was limited to the first 2 years after diagnosis [10]. This report extends prior findings, confirming the validity of the formula up to the 5th year after diagnosis, and shows that the definition of prognosis can be significantly improved by taking into account dynamic elements which reflect the course of the disease and the response to conventional treatment during the first 8 months after diagnosis.