Cytogenetic follow-up of 100 patients submitted to bone marrow transplantation for Philadelphia chromosome-positive chronic myeloid leukemia. Cooperative Study Group on Chromosomes in Transplanted Patients.

100 Ph+ CML patients submitted to BMT were studied cytogenetically before grafting and serially after transplantation. The 12 European institutions participating in the study, including transplant units and laboratories of cytogenetics, collected a total of 520 studies. The Ph chromosome was observed after BMT in 22 patients who did not enter relapse during the observation time (10-1400 days--median 420 d) following initial detection of the chromosome. This abnormality was observed in 1 to 30% of the cells analyzed. In 10 patients, abnormal cells were detected only within the first 90 d after BMT, in 5 patients both before and after 90 d and in 7 patients only after 90 d. 44% of these 22 patients had a moderate-to-severe cGVHD. Future studies are needed in order to better evaluate the real incidence of persistent disease and the correlations with the GVHD.