Controversial issues in
chronic idiopathic myelofibrosis (
IMP) are amongst others the evolution of the disease process and the influence of
therapy on the dynamics of
fibrosis. For this reason, a multicenter observational study was performed on 309 patients with IMF that had a long follow-up including 822 bone marrow biopsies at a median interval of 32 months. In addition to a control group (156 patients) with symptomatic treatment, monotherapy consisted of
busulfan (30 patients),
hydroxyurea (52 patients),
interferon (26 patients) and various combinations (48 patients). Density and quality (
reticulin/
collagen) of fibers was determined by a semiquantitative scoring system. Independent of therapeutic regimens at the time of the last bone marrow biopsy 67% of the patients with grades 0-2
fibrosis revealed a progression, 42% stable state and 6% regression of
myelofibrosis. Because of significant differences concerning frequencies of biopsies and endpoints of examinations, individual changes in the grades of
fibrosis were evaluated with regard to treatment applied at standardized intervals of 20 months. According to this calculation no relevant differences in the dynamics of
myelofibrosis (progression, stable state) was detectable in the control group compared to the other therapeutic modalities. The few patients with a regression of
myelofibrosis usually presented with severe hypoplasia compatible with a myelo-ablative effect by aggressive
chemotherapy. In conclusion, persuasive evidence has been produced that
myelofibrosis in IMF is characterized by a stepwise progression and that this process is not significantly influenced by current treatment strategies.