CML Glossary ‘B’



*Basophil = a type of myeloid white

blood cell which is often elevated in CML.


*bcr = breakpoint cluster region – a gene on human chromosome # 22 which is involved in the pathophysiology (abnormal functioning) of CML.


*bcr-abl = the abnormal gene that characterizes the leukemic stem cells of most people with CML. For CML to occur, the “abl” gene (named after the researcher Abelson) must come unglued from its usual location on chromosome # 9, and become attached to the “bcr” (breakpoint cluster region) of

chromosome #22, thus creating the bcr-abl hybrid, or “chimera” which has a number of nasty properties. It appears that the genetic “mistake” producing bcr-abl is quite common and may occur several times during the lives of normal people; however, their immune systems recognize and kill the abnormal cells. This fails to happen in people who develop CML, but it is not known why.


Bioethics = the application of ethics to the science and practice of biology including medicine, especially as applied to human and animal life


Biopsy = see bone marrow biopsy


*Blast (or blastic) phase = the third phase of CML after chronic and accelerated phases, characterized by the presence of increasing numbers of highly immature blood cells ( “myeloblasts,” or “blasts”) in the blood, bone marrow and other organs. Blast phase is often, but not always, fatal within months, though new treatments show promise in prolonging survival. It is believed that blast phase is reached when the CML cells have reached a critical mass of mutations which put them beyond all the body’s control mechanisms.


*BMA = bone marrow aspiration


*BMB = bone marrow biopsy


BMT = bone marrow transplant


*Bone marrow = the central portion of our bones, where the majority of blood cells types are made and stored. Bone marrow contains many other types of tissue besides blood cells, including a fine meshwork of bone (“spicules”), connective tissue, and blood vessels.


*Bone marrow aspiration (BMA) = a procedure in which liquid contents of a patient’s bone marrow are withdrawn (aspirated) through a needle.  This procedure is used to make the diagnosis of CML and, now, sometimes used to follow the progress of treatment of CML.


*Bone marrow biopsy (BMB) = similar to a bone marrow aspiration, but used less frequently and performed with slightly different equipment. It is used when a larger or different kind of sample of marrow is needed, or when a BMA is unsuccessful because the marrow is too fibrous to permit aspiration through the BMA needle.


*Bone marrow transplant (BMT) = a procedure in which bone marrow is taken from one person and given to another, for therapeutic purposes. In fact, this procedure is rarely used in CML nowadays, having been largely replaced by stem cell transplants (SCT’s); however, many people still use the term BMT even when they’re referring to an SCT.


Bosulif = branded name of bosutinib, a TKI from Pfizer.


Bosutinib = the generic name of a second generation tyrosine kinase inhibitor.  In Canada, this TKI can only be prescribed after failure to respond appropriately to first-line TKIs.


BUN = Blood Urea Nitrogen (a measure of kidney function).


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