BCR and acute lymphoblastic leukemia: The difference between the frequency of BCR/ABL1 rearrangement (3.5% for ALL IC 2002 and 1.4% for ALL IC 2009) was because some of the children with ALL Ph+ were treated with the EsPhALL (European intergroup study on postinduction treatment of ALL Ph+) protocol, in which imatinib was incorporated into combination chemotherapy regimens from 2012/2013.