Understanding CML

Chronic Myelogenous Leukemia (CML) is referred to by a variety of names, such as chronic granulocytic, chronic myelocytic, or chronic myeloid leukemia.  It is one of the more rare forms of leukemia and can go undetected for great amounts of time without acute symptoms.

 

CML is sometimes discovered through routine blood tests during a normal check-up or physical.  It may first appear as anemia, with the patient finding colds and other minor irritations difficult to control.  A complete blood count can rule out other disorders and indicate a need to conduct additional tests to confirm the CML diagnosis.

CML is an acquired leukemia, resulting from a change in a person's DNA.  This change results in an uncontrolled growth of white cells.  This uncontrolled growth can bring about abdominal discomfort due to an enlarged spleen.  Other symptoms may include excessive sweating (night sweats), weight loss, and an increased sensitivity to warm temperatures.
 

 

When CML is suspected following a complete blood count, doctors will generally perform a series of tests referred to as a Cytogenetic Analysis.  A small sample of bone marrow is acquired via a marrow aspiration (BMA) and, at times, a bone biopsy will be performed (BMB).  The Cytogenetic Analysis measures the number and structure of the chromosomes.  CML is confirmed with the discovery of the PH Chromosome.  The PH Chromosome (Philadelphia Chromosome) is detected by a shortened chromosome number 22 and the translocation (or exchange) of 22's genetic material with chromosome number 9. (see illustration below)

 

Presence of a high white count, the PH Chromosome, and other blood and marrow tests can confirm a diagnosis of CML.


How the Philadelphia Chromosome is formed.


CML has three phases: 1) chronic phase; 2) accelerated phase: and 3) blastic or blast crisis.  
(CML does NOT have "stages" like other cancers.)

 

Chronic phase, the beginning phase in which most patients (approximately 80%) are diagnosed, presents with symptoms being less severe due to the cell's ability to continue to develop into functioning white cells and platelets. 


Accelerated phase marks a point in which the "disease load" has increased.  Generally, at this phase, blast cells (immature white blood cells) make up 10% to 15% of peripheral blood or bone marrow.  More symptoms may begin to appear and platelet levels may begin to fluctuate erratically. 


Blastic (or Blast Crisis) is the most advanced phase of the disease and is indicated by a blast percentage greater than 30%.  Symptoms include those mentioned above, as well as bone pain, infection, acute bruising and bleeding.  Bruising and seepage of blood into the skin is a primary feature of this phase.  Some patients may also experience extreme fatigue, shortness of breath, and abdominal pain.  Blast crisis closely resembles acute leukemia and has a survival range of three to six months.

 

Not all healthcare professionals may agree with or follow these cutoff points for the different phases. Specific questions about what phase you are in should be discussed with your treating hematologist or oncologist.