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.