Chronic myelogenous leukemia in the lymphoid blastic phase: characteristics, treatment response, and prognosis.

PURPOSE: To determine the clinical and laboratory characteristics and outcomes of patients with chronic myelogenous leukemia (CML) in the lymphoid blastic phase. PATIENTS AND METHODS: Data from 296 patients with CML blastic-phase disease who were referred to our institution between 1967 and 1991 were analyzed. Sixty-eight patients had CML lymphoid blastic-phase disease. Pretreatment characteristics, responses to different therapies, and survival rates were evaluated.
RESULTS: Compared with patients having myeloid or undifferentiated blastic-phase disease, those with lymphoid morphology were significantly younger, presented with significantly lesser degrees of anemia, lower white blood cell and peripheral blast counts, higher percentages of marrow blasts, lower lactic dehydrogenase levels, and higher albumin levels. Accelerated-phase CML preceded the blastic phase in 40% of patients with lymphoid disease, compared with 54% of those with other morphologic findings (p = 0.03). The common acute lymphocytic leukemia antigen (CALLA) was expressed on lymphoid blasts in 97% of patients. The incidence of chromosomal abnormalities was similar in the three morphologic categories, although patients with lymphoid disease tended to have a lower incidence of trisomy 8 (17% versus 27%; p = 0.10) and of isochromosome 17 abnormalities (10% versus 17%; p not significant). The incidence of lymphoid blastic phase disease has not increased over the past decade, and it is not higher in patients with the chronic phase of the disease treated with alpha interferon. Patients with lymphoid disease had a significantly higher response rate to chemotherapy during the first salvage (49% versus below 20% for other morphologies; p < 0.001), particularly with vincristine, Adriamycin, and dexamethasone therapy (complete response rate of 61%). Survival during the blastic phase of the disease was also significantly longer in patients with lymphoid morphology than in those with other morphologies (median survival of 9 months versus 3 months; p = 0.01). The benefit associated with lymphoid blastic-phase morphology is brief, and plans for allogeneic bone marrow transplantation or experimental maintenance or consolidation programs should be implemented rapidly.
CONCLUSIONS: Patients with CML lymphoid blastic-phase disease have different clinical and laboratory features than patients with other blastic-phase morphologies. In patients developing CML blastic-phase disease, distinguishing those with lymphoid transformation is extremely important because of the different therapeutic requirements (acute lymphocytic leukemia-type therapy) and prognostic implications.