Effect of diagnosis (refractory anemia with excess blasts, refractory anemia with excess blasts in transformation, or acute myeloid leukemia [AML]) on outcome of AML-type chemotherapy.

In current medical practice, patients with refractory anemia with excess blasts in transformation (RAEB-t), and especially patients with RAEB, receive chemotherapy regimens (AML Rx) administered to patients with acute myeloid leukemia (AML) less often than do patients with AML. These entities are distinguished primarily by marrow blast percentage (5% to 19% RAEB, 20% to 29% RAEB-t, and > or = 30% AML). The poor prognosis of many RAEB or RAEB-t patients, if untreated, led us to give them AML Rx using the same plan as for AML. The purpose of this analysis was to see if diagnosis (RAEB, RAEB-t, or AML) affected outcome. We treated 372 patients with AML (acute promyelocytic leukemia [APL] excluded), 106 with RAEB-t, and 52 with RAEB. AML Rx produced a 62% complete remission (CR) rate in RAEB, essentially identical to the rates in RAEB-t and AML, but event-free survival (EFS) from CR and from start of treatment (start of Rx), as well as overall survival, were poorer in RAEB than in AML or RAEB-t, with AML and RAEB-t being identical. However, patients with RAEB or RAEB-t were more likely to have poor prognostic characteristics, in particular complex abnormalities involving chromosomes 5 and/or 7. Multivariate analyses indicated that, when considered together with cytogenetics and other patient characteristics, a diagnosis of RAEB rather than AML or RAEB-t had no effect on EFS from start of Rx, EFS from CR, survival, or achievement of CR. These analyses suggested a trend for patients with RAEB-t to have better EFS from start of Rx than patients with AML or RAEB (P = .08; relative risk, 0.80; 95% confidence interval, 0.62 to 1.03), but there were no differences with respect to the other outcomes. Our data suggest that the propriety of administering AML Rx to patients with RAEB or RAEB-t who have poor prognosis without treatment is identical to the propriety of treating AML in this fashion. Deterrents to standard AML Rx in these patients could justifiably include cytogenetics, age, etc, but not a diagnosis of RAEB or RAEB-t per se.