Childhood leukemia: Understanding the significance of chromosomal abnormalities

The survival for children with acute lymphoblastic leukemia (ALL) has increased from 3% to greater than 70% in the last 30 years, with some patients achieving 95% survival. These advances have been made not only because therapy has improved, but also because there is a much greater understanding of the diversity of ALL. The identification of clinical and biological prognostic factors associated with ALL has resulted in the formation of subsets of patients classified into risk groups. Although age, initial white blood cell count, and central nervous system or testicular disease are all important prognostic factors, cytogenetic abnormalities have now emerged as the single most important prognostic factor for children with ALL. There are specific cytogenetic findings in the leukemic blast cells of these children that influence their prognosis. Some of these findings are positive factors and some adverse. Treatment protocols for ALL today are now determined by these specific chromosomal abnormalities.