PHILADELPHIA CHROMOSOME-NEGATIVE CHRONIC MYELOGENOUS LEUKEMIA WITH REARRANGEMENT OF THE BREAKPOINT CLUSTER REGION - LONG-TERM FOLLOW-UP RESULTS

Background. Five to 10% of patients with chronic myelogenous leukemia (CML) do not have the Philadelphia chromosome (Ph), but one-third of t hem have rearrangements of the breakpoint cluster region (BCR-positive ). Methods. The authors analyzed the characteristics, treatment respon se, and prognosis of 23 patients with BCR-positive, Ph-negative CML, a nd compared them with patients with Ph-positive CML, Ph-negative BCR-n egative CML and chronic myelomonocytic leukemia (CMML) treated during the same period. Results. Seventeen patients had early chronic phase C ML, 3 had late chronic phase, 2 had accelerated phase, and 1 had blast ic phase. The median age was 44 years (range, 14-71 years), median pla telet count was 402 X 10(9)/l, and median leukocyte count was 86 X 10( 9)/l. Fourteen of the 17 patients with early chronic phase CML receive d alpha-interferon; 12 (86%) achieved complete hematologic remission. Median survival in chronic phase CML was 60 months (range, 3-90+ month s). Patients with Ph-negative BCR-positive CML and those with Ph-posit ive CML had similar characteristics and outcome. Compared with patient s with Ph-negative BCR-negative CML and CMML, patients with Ph-negativ e BCR-positive CML and Ph-positive CML were significantly younger, had a significantly higher incidence of leukocytosis, thrombocytosis, and peripheral and marrow basophilia, and a significantly lower incidence of anemia, thrombocytopenia, marrow blast percent, and peripheral and marrow monocytosis. The median survival was 60 months for Ph-negative BCR-positive CML, 73 months for Ph-positive CML, 25 months for Ph-neg ative BCR-negative CML, and 9 months for CMML (P < 0.001), When analyz ed adjusting for their stage, patients classified with Ph-negative BCR -positive CML Stage I disease had a significantly better survival than did patients with Ph-negative BCR-negative CML (P < 0.02). Conclusion s. Patients with Ph-negative BCR-positive CML are similar to those wit h Ph-positive CML and should be treated with the same approaches.