- Delayed intensification therapy II: All patients receive therapy as in delayed intensification I, arm I. CNS3 patients also receive radiotherapy for 3-10 days, beginning on day 29. All other SER patients, patients with MLL rearrangements, and some patients pretreated with steroids (> 48 hours within the week prior to diagnosis) receive prophylactic cranial radiotherapy (CRT) for 8 days, beginning on day 29. Patients then proceed to maintenance therapy.