Treatment of patients with acute promyelocytic leukemia. The EORTC-LCG experience. EORTC Leukemia Cooperative Group.

Acute promyelocytic leukemia (M3) is, as one of the FAB subtypes of AML, included in the EORTC/GIMEMA AML-8A and 8B randomized trials. In these trials 1519 patients were included, 477 of them in non-Italian EORTC-LCG centers and 1042 in GIMEMA centers. A total of 80 patients were classified as M3 including 18 patients with M3-variant. Thirty-nine were male and 41 female. Ages ranged from 15 to 59 years; 25 (31.3%) of them were younger than 30, 34 (42.5%) between 30 and 45, and 21 (26.3%) older than 45 years of age. 56.3% of the patients had leukocytes less than 5 x 10(9)/l at the time of diagnosis vs. 24.9% of the patients belonging to the other FAB subtypes. Remission induction consisted of a standard protocol with 3 days daunorubicin and 7 days of cytosine arabinoside. Forty-three patients (53.8%) achieved a complete remission compared to 64.6% of the remaining AML patients. After salvage treatment this percentage increased to 70%, which is the same as for the other AML subtypes. Thirteen (16.3%) patients died during remission induction, mainly due to hemorrhagic complications. This percentage is significantly higher than the death rate (9.1%) in the other FAB subtypes of AML. All patients received one course of consolidation treatment. Post consolidation treatment could be either standard maintenance, intensive consolidation courses, autologous or allogeneic transplantation, according to the guidelines of the treatment protocols. At present, relapses almost all in the bone marrow, are seen in only 34.9% of the M3 patients, compared to 48.4% in the remaining AML patients. Disease-free survival for patients less than 45 years of age with the M2 and M3 subtypes was approximately 50% at 3 years compared to 30-40% for the other FAB subtypes. Despite the higher death rate during induction, the long-term survival results were better for M3 patients in comparison with the remaining AML patients. The projected survival at 3 years was 50% for M3 patients vs. 38% for remaining patients.