Early response to induction is predictive of survival in childhood Philadelphia chromosome positive acute lymphoblastic leukaemia: Results of the Medical Research Council ALL 97 trial.

We report the outcome of children with Philadelphia positive acute lymphoblastic leukemia (Ph+ ALL) treated on the national trial for childhood ALL, MRC ALL 97/99, between Jan 1997 and Jun 2002. A diagnosis of Ph+ ALL was made by karyotyping and/or fluorescent in situ hybridisation. Outcome was evaluated according to NCI risk criteria and treatment response. Statistical methods included Kaplan Meier analysis, logrank and stratified logrank tests. Of the 1937 patients treated on the MRC ALL 97/99 protocol, 1836 were successfully screened for Ph chromosome and 42 (2.3%) were positive. This subgroup of patients was heterogeneous at the cytogenetic level with 27 (77%) out of 35 assessable cases having one or more abnormality in addition to the Ph translocation. Four recurrent secondary abnormalities were observed: an extra Ph chromosome, loss of 9p (del 9p), high hyperdiploidy and monosomy 7. The median age at diagnosis and presenting white cell count were 6.8 years and 32.5 × 10 9 /L respectively. 19 (45%) had