title: The significance of an M2 bone marrow at cessation of chemotherapy in childhood acute lymphoblastic leukemia.
abstract: The decision to cease chemotherapy in childhood acute lymphoblastic leukemia (ALL) is taken when clinical examination and investigations at the end of the predetermined treatment period show no evidence of residual disease. Since 1972, 11 children treated at this institution have not fulfilled the criteria for cessation of therapy in that they all had elevated blast counts in their bone marrows at "off-treatment" studies (i.e., an M2 marrow, defined as 5-25% blasts). Initially, the significance of this finding was not appreciated and the first child in this series received a further 2 years of chemotherapy. Subsequently the relevance of such an M2 marrow to remission status was questioned and the next 10 patients were simply observed and their bone marrows were reexamined after an interval of 4-12 weeks. Nine of these 11 remain in continuous complete remission with a follow-up of 5-15 years from diagnosis. It is postulated that this finding represents an immunologic rebound phenomenon and is not related to potential for later relapse.
authors.affiliation: Department of Paediatric Oncology, Adelaide Children's Hospital, Inc., South Australia.
authors.forename: K
authors.initials: K
authors.lastname: Pritchard-Jones
authors.forename: I R
authors.initials: IR
authors.lastname: Toogood
authors.forename: M S
authors.initials: MS
authors.lastname: Rice
mesh_terms: D001854:Bone Marrow Cells; D002648:Child; D002675:Child, Preschool; D002985:Clinical Protocols; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000188:drug therapy*; D012008:Recurrence; D012074:Remission Induction; D012307:Risk Factors