Background: Bone marrow (BM) finding on day 7 of induction chemotherapy is one of major prognostic factors in acute lymphoblastic leukemia (ALL). M3 marrow (blast ＞25% on BM examination) on day 7 is associated with lower survival rates, compared with M1 (blast ＜5%) or M2 (blast 5∼25%) marrow. Herein, we analyzed the effect of the augmented post-induction chemotherapy in patients with high-risk ALL with M3 marrow on day 7 BM examination. Methods: Patients diagnosed as high-risk ALL and received modified Children's Cancer Group (CCG)- 1882 induction chemotherapy between January 1996 and October 2005 at Seoul National University Children's Hospital were analyzed. Patients with M1 or M2 marrow on day 7 were treated with modified CCG-1882A/B chemotherapy from consolidation and patients with M3 marrow were treated with modified CCG-1882C chemotherapy. Results: Total 44 patients (29 with modified CCG-1882A/B and 15 with modified CCG-1882C) were analyzed. The overall survival (OS) and 5-year event-free survival (EFS) were 86.2% and 81.9%, respectively. The OS of the patients who were treated with modified CCG-1882A/B protocol (88.9%) was not different from that of the patients with modified CCG-1882C protocol (80.0%) (P=0.3256). Also, there was no statistical difference in 5-year EFS of both groups (85.4% vs 72.7%, P=0.2117). Conclusions: There was no difference between survival of the patients with M1/M2 marrow on day 7 BM examination and M3 marrow after augmented post-induction chemotherapy in patient with high-risk ALL. We suggest that poor prognosis of high-risk ALL with poor initial response could be overcome by augmented post-induction chemotherapy. (Korean J Hematol 2008;43:238-246.)

Keywords: High-risk acute lymphoblastic leukemia, Augmented post-induction chemotherapy, Childhood, Response, Prognosis, Survival rate