Low incidence of CNS relapse with cranial radiotherapy and intrathecal methotrexate in acute lymphoblastic leukemia.

OBJECTIVES: To assess the incidence of isolated central nervous system (CNS) relapses in patients of acute lymphoblastic leukemia (ALL) treated with a protocol containing cranial irradiation and intrathecal methotrexate as CNS directed therapy.

DESIGN: Prospective non randomized study.

SETTING: Department of Medical Oncology, Tata Memorial Hospital.

SUBJECTS: 623 children of ALL on MCP 841.

METHODS: CNS relapse was diagnosed, if upon examination of the CSF, more than 50 cells/microliter were observed, or a count of 5 cells which were unequivocally lymphoblasts.

RESULTS: The incidence of isolated CNS relapse was 1.75% with the use of this treatment. Age, sex, white blood cell count, platelet count, lactic dehydrogenase and immunophenotyping were not significantly related to isolated CNS relapse.

CONCLUSION: A low incidence of isolated CNS relapse demonstrates the adequacy of the presymptomatic CNS therapy.