DNA-Ploidy - A Prognostic Factor of Acute Lymphoblastic Leukemia (ALL) in Childhood

A number of studies have shown that the DNA-ploidy of mononucleated blood cells is a prognostic factor of acute lymphoblastic leukaemia in childhood, patients with an hyperploid DNA index showing a significantly better response to chemotherapy than those with a euploid DNA index. The aim of the present study was to re-evaluate this question for a subset of patients in the German-Austrian-Swiss ALL-BFM study, treated between 1984 and 1996. The DNA index was flow cytometrically determined in mononucleated blood cells from the bone marrow and/or peripheral blood of 104 children with acute lymphoblastic leukaemia. High-risk patients receiving more intensive treatment were excluded from the study. The recurrence-free survival of patients with hyperploid and euploid tumours was analyzed according to Kaplan and Meier, and the results were compared with those for other possible prognostic factors. Data analysis, incl. multivariate analysis, showed that DNA ploidy was indeed of significant prognostic value, with a risk ratio similar the initial leukocyte count. The appropriate cut-off point between diploid/near-diploid and hyperdiploid cases seems to be a DNA index of 1.10 rather than the most widely used 1.16. Overall, we are of the opinion that future studies should continue to include the DNA ploidy as a possible prognostic factor for acute lymphoblastic leukaemia in childhood.