INTENSIFICATION OF TREATMENT AND SURVIVAL IN ALL CHILDREN WITH LYMPHOBLASTIC-LEUKEMIA - RESULTS OF UK MEDICAL-RESEARCH-COUNCIL TRIAL UKALL-X

The UK Medical Research Council trial MRC UKALL X was designed to inve stigate the benefit of one or two courses of additional intensificatio n therapy in children with acute lymphoblastic leukaemia receiving sta ndard treatment. From 1985 to 1990 1612 children, comprising more than 90% of eligible cases in the UK, were treated with intensive inductio n therapy, central nervous system directed therapy with cranial irradi ation and intrathecal methotrexate, and continuing treatment for 2 yea rs. 1171 children were randomised to receive additional intensificatio n therapy at 5 weeks, 20 weeks, both, or neither. At follow-up of at l east 3 years disease-free survival for all children at 5 years was 62% (95% confidence interval [Cl] 60.0-64.4), a significant improvement o ver the 56% (53.0.59.6) found in the preceding MRC UKALL trial. The 5- year disease-free survival was 71% (65.5-76.1) for children randomised to two blocks of intensification therapy, this being significantly be tter than the 62% (56.6-68.0), 61% (55.7-67.1), and 57% (50.9-62.7) ra tes for the groups randomised to one intensification block at 5 weeks, one at 20 weeks, and no intensification, respectively. The benefits o f intensification therapy were seen irrespective of clinical factors k nown to influence outcome such as age, sex, and initial leucocyte coun t. We conclude that the addition of two courses of intensification the rapy has produced a 14% improvement in disease-free survival and an 11 % improvement in overall survival for the randomised patients. This ad ditional treatment is of benefit to all children with acute lymphoblas tic leukaemia, even those traditionally deemed at lower risk of relaps e.