Analysis of treatment in childhood leukaemia. V. Advantage of reduced chemotherapy during and immediately after cranial irradiation

Authors:
  • IMI C MacLennan
    I C MacLennan
  • JPJ Peto
    J Peto
  • HKH E Kay
    H E Kay
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Abstract
This paper compares antileukemic efficiency with toxicity to the patient of chemotherapy during and immediately after CNS irradiation. The drug regimen consisted of daily mercaptopurine (MP) and weekly methotrexate (MTX) at the maximum tolerated dose. Of 140 patients with acute lymphoblastic leukemia allocated to receive this drug regimen during and after cranial irradiation, 8 died in complete remission within 6 mo. of the end of irradiation. Details of the nature of these deaths are given. This result led the Working Party to modify the chemotherapy scheduled for this stage in treatment. The modified chemotherapy consisted of MP at reduced dosage before and during cranial irradiation and omission of MP and MTX for 3 wk after irradiation, during which time daily prednisolone with 2 doses of vincristine were substituted. Following that, treatment reverted to the orginal schedule of daily MP and weekly MTX at maximum tolerated dose. Of 109 patients allocated to this modified regimen only 1 died in remission within 24 wk after cranial irradiation. Analysis of the antileukemic effect of the modified regimen showed that up to 600 days it was at least as effective as the original more intensive regimen. There is a definite advantage in keeping chemotherapy to a minimum during and immediately following cranial prophylactic irradiation.