Study Of Clinical Characteristics And Treatment Outcomes In Children With Acute Lymphoblastic Leukemia With T(12; 21)

Objective To study the clinical characteristics and treatment outcomes in children with newly treated acute lymphoblastic leukemia (ALL) with t (12; 21)to increase the knowledge about childhood ALL with t(12; 21) and improve the treatment outcomes. Methods Fluorescence in situ hybridization(FISH) and/or reverse transcriptase-polymerase chain reaction(RT-PCR) were used to find ALL with t(12; 21), we analysed their clinical and biological characteristics by comparing with t(12; 21) negtive children. Retrospectively we analysed consecutive 196 children with newly treated ALL in our hospital from January 2003 to June 2007. Survival rates were estimated by Kaplan-Meier method and prognostic factors were evaluated by Cox regression with SPSS14. 0. Results t(12; 21)/ TEL-AML1 fusion gene was found in 29 cases by FISH or PCR, accounting for 14.8% and 16.8% in childhood ALLs and in B lineage ALL cases, respectively. The median age at diagnosis was 5(2 to 11)years. All of the t(12; 21) patiens expressed B lineage immunophenotype, and all of them were commonB-ALL. High myeloid antigen coexpression was found. In 26 CCA cases, no t (12; 21) was found. TEL allele deletion was found in 17(58.6%) of t (12; 21) positive cases by FISH. By comparison, no statistic difference was found in sex, anemia, hemorrhage, organ enlargement, initial white blood cell count (WBC) and LDH between the positive and negative B lineage ALLs, but the platelet count was lower in positive cases. Moreover, no difference was found in overall CR rate, CR duration, relapse rate and death rate between the two groups. By Kaplan-Meier analysis, the 4-year overall survival (OS) rate was (0. 917±0. 057) and (0.753±0.054), respectively (Log Rank Test P=0.390). The 3-year disease free survival (DFS) rate was (0.920±0.054) and (0.823±0.042), respectively(Log Rank Test P=0.506). The 3-year event free survival (EFS) rate was (0.920±0.054) and (0.814±0.042) , respectively (Log Rank Test P=0.608). Multivariate analysis demonstrated a significant poor relationship between higher WBC at diagnosis with OS, DFS and EFS(P=0.05, respectively). Conclusion t(12; 21) was the most common chromosomal translocation in childhood ALL, but not all of them could be detected by CCA. t(12; 21)cases showed B lineage immunophenotype. TEL allele deletion was common in these cases. There was no significant difference in clinical characteristics , short term outcomes and long term outcomes between the t (12; 21) ALLs and the TEL-AML1 negative cases, but the positive group had shown some superiority at OS. In our data, Chinese t (12; 21) ALL showed older in age, lower IgH rearrangement frequency as compared with the reports abroad. WBC was the only factor affecting survival rates(P=0.05) of all patients with t(12; 21).