Standardization of flow cytometric minimal residual disease evaluation in acute lymphoblastic leukemia: Multicentric assessment is feasibleThe data given in this work are the results of the AIEOPBFMALLFCMMRDStudy Group.How to cite this article: Dworzak MN, Gaipa G, Ratei R, Veltroni M, Schumich A, Maglia O, Karawajew L, Benetello A, Potschger U, Husak Z, Gadner H, Biondi A, Ludwig WD, Basso G. Standardization of flow cytometric minimal residual disease evaluation in acute lymphoblastic leukemia: multicentric assessment is feasible. Cytometry Part B 2008; 74B: 331–340.

Background:Singlelaboratory experience showed that flow cytometric FCM assessment of minimal residual disease MRD in acute lymphoblastic leukemia ALL is feasible in most patients and gives independent prognostic information. It is, however, not known whether FCM analysis can reliably be standardized for multicentric application.Methods:An extensive standardization program was installed in four collaborating laboratories, which study FCMMRD in children treated with the AIEOPBFMALL 2000 protocol. This included methodological alignment, continuous quality monitoring, as well as personnel education by exchange and performance feedback.Results:Blinded interlaboratory tests of listmode data interpretation concordance n 202 blood and bone marrow samples from followup during induction of 31 randomly selected patients of a total series of n 395 showed a very high degree of interrater agreement among the four centers despite differences in cytometers and software usage intraclass correlation coefficient ICC 0.979 based on n 800 single values. Lower concordance was reached with amounts of MRD below 0.1. Comparing data from sample exchange experiments n 42 samples; ICC 0.98 and from independent patient cohorts from the four centers regarding positive samples per timepoint of followup as well as risk estimates concordance was also good.Conclusion:MRDevaluation by FCM in ALL can be standardized for reliable multicentric assessment in large trials. © 2008 Clinical Cytometry Society.