Introduction

The improvement in outcome of treatment for childhood leukaemia has been both consistent and sustained over the past 33 years. Much of that improvement has been a consequence of the series of clinical trials run by the Medical Research Council Childhood Leukaemia Working Party and its successor groups. Some improvement has undoubtedly also been due to improvements in supportive care, which have—especially in the case of acute myeloid leukaemia—made it possible to deliver very intensive therapy that would previously have led to an unacceptable level of treatment-related mortality and morbidity.

The paper by Shah et al1 demonstrates how the proportion of patients recruited to clinical trials in childhood leukaemia has gradually risen over a 33-year period, so that for ALL the proportion has increased from 57% in the era of UKALL 8 to 88% in the most recently closed trial, ALL2003. During the period encompassing these trials, the event-free survival (‘event’ in this context meaning relapse or death either from disease or another cause) has risen from around 50% in UKALL 8 to around 85% in ALL2003.2 Intriguingly, this success has not been the result of incorporation of novel drugs into treatment regimens—all the agents currently in use have been available in routine clinical practice for decades—but rather through the systematic evaluation of outcomes in relation to clinical and latterly other biological factors, such as immunophenotyping and cytogenetics, in the context of large multicentre clinical trials in the UK, North America and mainland Europe.3–5 Gratifying though this improvement may be, there remain problems to be resolved that will require further clinical trial activity.

Current clinical issues include the continued improvement of identification of high-risk and low-risk groups, reduction of treatment-related mortality and morbidity, the role of bone marrow transplantation and the need for new drugs. Other problems facing …