Intensification of treatment for adults with acute lymphoblastic leukaemia: results of U.K. Medical Research Council randomized trial UKALL XA. Medical Research Council Working Party on Leukaemia in Adults.

The MRC UKALL XA trial for patients aged 15 years and over with acute lymphoblastic leukaemia was designed to evaluate short blocks of intensive 'AML-style' treatment. Between 1985 and 1992, 618 eligible patients were entered into the trial. 450 patients were randomized to receive early intensification at 5 weeks, late intensification at 20 weeks, both, or neither. Unlike the concurrent children's trial, UKALL X, which was of similar design, UKALL XA does not demonstrate a clear benefit for intensification, although there was a significant reduction in the relapse risk due to the early block. The estimated increase in disease-free survival at 5 years was 2% with 95% confidence interval from 1% reduction to 5% increase. There may be a real difference between the effect of these treatments in adults and in children, but this result may be somewhat weakened by poorer compliance, with a greater proportion of adults not receiving the treatment arm to which they were randomized.