7. The definitions of CML phases are as follows: clonal evolution defined as the presence of additional chromosomal abnormalities other than the Ph chromosome is part of accelerated phase CML. Ph chromosome variants or complex Ph chromosome translocations are not considered to indicate disease acceleration. We have recently found clonal evolution to have a variable prognostic impact and may be suppressed with IFN-a therapy. Hence these patients will be eligible if no other accelerated phase signs are present, and analyzed separately.