[Dynamically monitoring minimal residual disease in acute leukemia after complete remission by multiparameter flow cytometry and its relation with prognosis].

This study was purposed to investigate the dynamically monitoring minimal residual disease (MRD) by flow cytometry (FCM) in patients with acute leukemia (AL) after complete remission and its relation with prognosis. From October 2010 to May 2012, 58 cases of AL (including 45 cases of AML and 13 cases of ALL) were regularly monitored for MRD in bone marrow by FCM and their bone marrow morphology was observed by light microscopy at the same time which continued to relapse or to follow-up deadline in the Department of Hematology, the First Affiliated Hospital of Zhengzhou University. Through average follow-up for 9 months (3 - 21 months), the average MRD level of patients with CR was got. And the prognostic value of MRD level at different time points in AL patients after CR was analysed and summarized. MRD ≥ 1% was defined as positive, otherwise, as negative. The results showed that the maximum and minimum MRD levels of 45 AML patients were 9.57% and 0.01% respectively, the average was 0.67%; the maximum and minimum MRD levels of 13 cases of ALL patients were 7.9% and 0.0016% respectively, the average was 0.99%. Among 44 cases after induction therapy, the relapse rate of MRD(+) group was 53.3% (8/15), the relapse rate of MRD(-) group was 10.3% (3/29), and the relapse rate of MRD(+) group was higher than that of MRD(-) group (χ(2) = 7.58, P = 0.006). Among 58 cases after the first consolidatory therapy, the relapse rate of MRD(+) group was 62.5% (5/8), the relapse rate of MRD(-) group was 16.0% (8/50), and the relapse rate of MRD(+) group was higher than that of MRD(-) group (χ(2) = 6.11, P = 0.013). It is concluded that MRD detected by FCM has a large range (10(-6) - 10(-2)), which can not be used as a single indicator of complete remission. When MRD ≥ 1% after induction therapy and the first consolidatory therapy, the relapse rate significantly increases, MRD can be used as a sensitive indicator for prognosis.