Frequencies of ETV6-RUNX1 fusion and hyperdiploidy in pediatric acute lymphoblastic leukemia are lower in Far East than West

Background. Both ETV6-RUNX1 (TEL-AML1) fusion and hyperdiploidy (>50 chromosomes) in transformed lymphoblasts are favorable genetic features in childhood acute lymphoblastic leukemia (ALL). Procedure. Among 433 Taiwanese children with ALL diagnosed at our hospitals between 1997 and 2007, the ETV6-RUNX1 fusion was found in 15.8%, and hyperdiploidy (>50 chromosomes) in 14.1% of the patients. These frequencies were lower than those reported in the West, leading us to conduct a metaanalysis of ETV6-RUNX1 fusion and hyperdiploidy frequencies in childhood ALL based on published reports. Results. The frequency of ETV6-RUNX1 fusion in the Far East (Japan, Korea, China, Hong Kong, Chinese in Singapore, and Taiwan) was 13.4% (177/1,321, range: 9-23%, median 13%), significantly lower than the 22.8% (1,664/7,291, range: 19-26%, median 23%) in the West (West Europe and the United States) (P<0.001, odds ratio=2.0, 95% CI: 1.7-2.4). Similarly, the frequency of hyperdiploidy in Japan and Taiwan was 14.3% (333/2,334, range: 12-20%,median 16%), significantly lower than the 25.2% in the West (5,173/20,510, range: 18-34%, median 23.5%; P<0.001, odds ratio=2.0, 95% CI: 1.8-2.3). Conclusions. This meta-analysis demonstrates lower frequencies of ETV6-RUNX1 fusion and hyperdiploidy among leukemia patients in the Far East compared with the West. The integral relationship of these genetic features with a favorable outcome in childhood ALL warrants further study of potentially important epidemiologic factors, including placental exposure to leukemogenic agents, and host pharmacogenetics.