Comparison of the effects of early intensified induction chemotherapy and standard 3+7 chemotherapy in adult patients with acute myeloid leukemia

Background Standard remission induction chemotherapy consisting of anthracycline plus cytarabine (3+7) is administered for adult acute myeloid leukemia (AML). However, the effects of intensified regimen on complete remission (CR), relapse and overall survival (OS) remain unknown. Methods We analyzed 1195 patients treated with idarubicin plus cytarabine/BHAC (3+7) from 2002 to 2013. Among them, 731 received early intensification with 3-day cytarabine/ BHAC (3+10, N=363) or 2-day idarubicin plus cytarabine/BHAC 3 days (5+10, N=368). The 3+10 and 5+10 strategies were applied to patients with bone marrow blast counts of 5-20% and > 20% on day 7 of 3+7, respectively. Results Early intensification correlated with a younger age (median: 40 vs. 45 yr) and higher t(8;21) frequency (20.4% vs. 7.1%), compared to 3+7. After early intensification, the early death rates were higher among the elderly (3+10 [15.7%], 5+10 [21.7%] vs. 3+7 [6.3%], P =0.038), while the post-induction CR rate was higher in young patients (3+10 [79.8%], 5+10 [75.1%] vs. 3+7 [65.1%], P < 0.001). Early relapse rate was also decreased (3+10 [11.8%], 5+10 [11.7%] vs. 3+7 [22.0%], P < 0.001). In multivariate analysis, early intensification correlated with an inferior 5-year OS among elderly patients (19.2% vs. 22.8%; hazard ratio [HR]=1.84, 95% confidence interval [CI]; 1.11-3.06, P =0.018) and lower overall relapse rate among young patients (33.0% vs. 41.4%, P =0.023; HR=0.71, 95% CI; 0.55-0.93, P =0.012). Conclusion Early intensification correlated with higher CR and lower relapse rates, but not OS in young AML patients. In elderly patients, early intensification correlated with a higher early death rate and poorer OS.