Prognostic factors in chronic myeloid leukaemia--importance of staging or disease biology.
The presenting clinical, haematological and cytogenetic features of 215 patients with a haematological diagnosis of chronic myeloid leukaemia (CML) were analysed with a view to defining prognostic factors. Of the 215 patients, 166 (77%) were found to be Philadelphia chromosome (Ph')-positive. The frequency of Ph' and complex Ph' abnormalities was similar for black and white patients. Black patients, however, had a significantly higher frequency of additional clonal chromosome abnormalities at presentation compared with whites (15/87 v. 1/79). Blacks also tended to present with more advanced disease, lower haemoglobin values, higher white cell counts, larger spleens and a higher frequency of lymphadenopathy and leukostasis. Median duration of survival from diagnosis of Ph'-positive patients was 44 months for whites and 30 months for blacks. The poorer survival of the black patients was in part accounted for by the poor survival of patients with additional clonal chromosomal abnormalities over and above Ph'. Black patients with only simple Ph' or complex Ph' had a similar survival to whites. In a multivariate analysis, the significant factors determining survival were: (i) the presence of additional clonal chromosomal abnormalities; and (ii) peripheral blast count over 5%, platelet count outside the normal range and haemoglobin value less than 10 g/dl. These factors defined subgroups of patients with median survival ranging from 12 months to 62 months. The inclusion of patients with variable prognoses needs to be taken into account when evaluating the results of new treatment modalities for CML.