Cytogenetic abnormalities and their prognostic significance in idiopathic myelofibrosis: a study of 106 cases.

The prognostic significance of cytogenetic abnormalities was determined in 106 patients with well-characterized idiopathic myelofibrosis who were successfully karyotyped at diagnosis. 35% of the cases exhibited a clonal abnormality (37/106), whereas 65% (69/106) had a normal karyotype. Three characteristic defects, namely del(13q) (nine cases), del(20q) (eight cases) and partial trisomy 1q (seven cases), were present in 64.8% (24/37) of patients with clonal abnormalities. Kaplan-Meier plots and log rank analysis demonstrated an abnormal karyotype to be an adverse prognostic variable (P<0.001). Of the eight additional clinical and haematological parameters recorded at diagnosis, age (P<0.01), anaemia (haemoglobin < or = 10 g/dl: P<0.001), platelet (< or = 100 x 10(9)/l, P<0.0001) and leucocyte count (> 10.3 x 10(9)/l; P=0.06) were also associated with a shorter survival. In contrast, sex, spleen and liver size, and percentage blast cells were not found to be significant. Multivariate analysis, using Cox's regression, revealed karyotype, haemoglobin concentration, platelet and leucocyte counts to retain their unfavourable prognostic significance. A simple and useful schema for predicting survival in idiopathic myelofibrosis has been produced by combining age, haemoglobin concentration and karyotype with median survival times varying from 180 months (good-risk group) to 16 months (poor-risk group).