OBJECTIVETo analyze the incidence, clinical characteristics and prognosis of childhood T-cell acute lymphoblastic leukemia (T-ALL).

METHODSFrom January 1999 to April 2005, 305 patients with newly diagnosed ALL were enrolled in protocol ALL-XH-99. The clinical characteristics of these children were analysed.

RESULTSOf 305 childhood ALL patients, 43 were T-ALL. There were 34 males among the 43 T-ALLs. The mean age at diagnosis was 7.8 (2.2 to 16.4) years, 29 (67.4%) cases of them were older than 10 years, and 27 (62.8%) cases had initial WBC count more than 50 x 10(9)/L. In comparison with that of B cell ALL (B-ALL), the percentages of age older than 10 years, initial WBC count more than 50 x 10(9)/ L, prednisone poor response (PPR), and failed to achieve remission at day 19 of induction chemotherapy in the T-ALLs were all higher. No statistic difference was found in sex between them. The eight-year event-free survival (EFS), relapse-free survival (RFS) and overall survival (OS) were (40.2 +/- 10.1)%, (51.4 +/- 11.6)% and (49.8 +/- 9.9)% for T-ALL, and (72.1-3.0)%, (83.2 +/- 2.7)%, and (76.6 +/- 2.9)% for B-ALL, respectively, being differed significantly between the two types of ALL (P < 0.01).

CONCLUSIONThere were statistic differences between T-cell and B-cell childhood ALLs in age, initial WBC count, early response to therapy, and eight-year EFS and RFS. Childhood T-ALL was associated with a worse prognosis than other sub-types of childhood ALL.