Molecular diagnosis and clinical decisions in adult acute leukemia.

A number of relatively new molecularly based diagnostic tests are now available to the physician involved in the treatment of patients with acute leukemia. These assays have considerable potential to improve prognostic accuracy, to aid in the selection of therapy, and to substantially enhance the ability to monitor results of treatment. Cytogenetic analysis now is the most important diagnostic test for determining prognosis and selecting therapy in acute myeloid leukemia (AML), and arguably, in acute lymphoblastic leukemia (ALL) as well. The accuracy of cytogenetics in many cases can be enhanced through the use of polymerase chain reaction (PCR)-based assays. Molecularly based assays of the leukemia cell's sensitivity or resistance to particular classes of drugs are beginning to emerge as potentially important tools for selecting therapies. Studies using molecular markers of disease to monitor response to therapy are yielding important clues about the biology of leukemia and are increasingly being used to guide therapy. The best uses of these new molecularly based assays are still uncertain and are the subjects of a large number of current clinic trials. While questions abound about their full potential, almost without question they will change the way we think about, diagnose, and treat leukemia.