MRC UKALL X. The UK protocol for childhood ALL: 1985-1990. The Medical Research Council Working Party on Childhood Leukaemia.

MRC UKALL X, the successor of UKALL VIII ran from 1985 to 1990 and accrued 1614 patients aged 0-15 years. After standard induction all children except those with initial white cell count greater than 100 x 10(9)/1 were randomised to one of four regimens; +/- early intensification +/- late intensification. CNS protection for all comprised cranial irradiation and intrathecal methotrexate with continuing treatment for two years. At a median follow up of four years the overall event free survival for all children is 66% (SE 1.5). This is a significant improvement over the previous MRC UKALL VIII trial. Age, sex and leucocyte count were highly significant prognostic factors. Analysis of the results indicates that the regimen containing both intensifications is superior. The strategy of early and late intensification has been adopted in the successor protocol MRC UKALL XI in which patients are additionally randomised to receive high dose methotrexate.