Information about Chronic Myelogenous Leukemia

Selina M. Luger, MD
Last Modified: November 1, 2001

Dear OncoLink "Ask the Experts,"
My father has a form of CML (Chronic Myelogenous Leukemia), but does not have the Philadelphia chromosome. The doctors say this is very rare. He has had four different chemo treatments since he was diagnosed over a year ago and has recently been admitted to the hospital for shortness of breath. Apparently his spleen is enlarged and is disrupting the movement of his diaphragm. Do you have any reports on his type of Leukemia?
Thank you for your time and consideration.

Selina M. Luger, MD, Director of the Leukemia Program and Assistant Professor of Medicine at the University of Pennsylvania, responds:

CML (chronic myelogenous leukemia) is classified as a myeloproliferative disorder. These are disorders, which result in overproduction of cells by the bone marrow resulting in high blood counts. CML or chronic myelogenous leukemia is a myeloproliferative disorder that results in the accumulation of excess numbers of white blood cells. Biopsies of the bone marrow (where cells are made) reveal that it is hypercellular — or packed with lots of extra cells. In classic CML, patients have an abnormal chromosome in their blood cells called the Philadelphia chromosome. This chromosome is a combination of chromosomes 9 and 22 which result in the creation of an abnormal gene called BCR-ABL. In order to be called CML we must find either the Philadelphia chromosome or the BCR-ABL gene.

It sounds like your father probably has blood counts and maybe bone marrow tests that look the same as someone with CML, but that they have not been able to find the chromosome or gene. This really falls into the category of myeloproliferative disorders. They may be classifying this as CML because until recently the treatment for CML and other similar myeloprolifertive disorders were the same and guided by the patient's blood counts, bone marrow, physical exam and symptoms. Now with the appearance of the new treatment Gleevec, it is important to tell classic CML apart from the other disorders because Gleevec only blocks the protein made by the bcr-abl gene. It will not work in varian forms of CML or other myeloproliferative disorders or leukemias