Comparison of three methods of central-nervous-system prophylaxis in childhood acute lymphoblastic leukaemia.

A retrospective comparison was made of three methods of central-nervous-system prophylaxis in childhood acute lymphoblastic leukaemia; (1) intrathecal methotrexate only; (2) intermediate-dose methotrexate infusion and intrathecal methotrexate and, (3) 2400 rads cranial irradiation and intrathecal methotrexate. The incidence of primary meningeal relapse was statistically significantly lower in both standard-risk patients (age grear than 24 months and less than or equal to 120 months white-cell count less than 20,000) and increased-risk patients (age less than or equal to 24 months or greater than 120 months and/or white-cell count greater than 20,000) whose central-nervous-system prophylaxis included cranial irradiation. The disease-free and overall survival of irradiated increased-risk patients was significantly better than that of unirradiated increased-risk patients. The disease-free survival of standard-risk patients who received intermediate-dose methotrexate was statistically superior to that of the remaining standard-risk patients. There were no significant differences in overall survival between the three groups of standard-risk patients.