COMPARISON OF FLUORESCENCE IN-SITU HYBRIDIZATION, CYTOGENETIC ANALYSIS, AND DNA INDEX ANALYSIS TO DETECT CHROMOSOME-4 AND CHROMOSOME-10 ANEUPLOIDY IN PEDIATRIC ACUTE LYMPHOBLASTIC-LEUKEMIA - A PEDIATRIC-ONCOLOGY-GROUP STUDY

Purpose: Chromosome abnormalities are an important prognostic factor i n childhood acute lymphoblastic leukemia (ALL). Recently, a subset of patients with hyperdiploid ALL and trisomy of chromosomes 4 and 10 has been reported to have a very favorable event-free survival. Rapid and accurate detection of these patients will allow them to be treated wi th highly effective and relatively nontoxic antimetabolite therapy. Be cause of inherent problems associated with conventional cancer cytogen etics, we examined the efficacy of fluorescence in situ hybridization (FISH) to identify this PILL subgroup. Patients and Methods: Fifty unc ultured bone marrow specimens from children with newly diagnosed ALL w ere examined for chromosomes 4 and 10 aneuploidy with FISH. These resu lts were compared with routine cytogenetics and DNA Index (DI).Results : Interphase FISH cytogenetics identified the abnormal cell line(s) in all cases in which cytogenetics showed aneuploidy of chromosomes 4 an d 10. In cases in which cytogenetics was not informative, FISH identif ied the presence of an aneuploid chromosome 4 and/or 10 cell line in c oncordance with the DI. Conclusions: FISH interphase cytogenetics can accurately detect chromosome 4 and 10 aneuploidy in leukemic cells. It is a rapid and clinically applicable technique that can reliably iden tify childhood ALL cases who have trisomy of chromosomes 4 and 10 and who have very favorable event-free survival.