Chronic Myeloid Leukemia (CML) is a chronic cancer of the blood that begins with a defect found in two chromosomes and which causes an over-production of white blood cells.  Everybody has 23 chromosomes, all containing DNA, which defines the person's genetic makeup.  Understanding of CML, which has been known since the 1800s, was changed in 1960 when something called the "Philadelphia chromosome" was discovered--so named because the researchers who discovered it, Dr. David Hungerford and Dr. Peter Nowell, were from Philadelphia. 

These doctors noticed that two patients with CML had an unusually small chromosome 22. Part of it was missing.  In 1972, Dr. Janet Rowley found the missing piece attached to the number 9 chromosome.  This was the first time a researcher had identified a chromosomal "translocation" in CML patients.  It's now known that the 9-22 translocation is in more than 95 percent of those patients with CML.  This discovery later led to an important treatment for CML.

Let's talk a bit about CML.  The cancer represents around 15 percent of leukemia cases in the nation, with nearly 4,600 cases diagnosed in 2007 alone.  According to the Leukemia & Lymphoma Society, more than 21,500 people currently are living with the affliction.  While it can strike at any age, most with it are over 50.

It's not known what causes CML in most cases.  However, it's felt that being exposed to high radiation doses increases your chance for getting the cancer.  There's not been discovered any hereditary link or a link with chemical exposure. Around 90 percent of people diagnosed with CML are diagnosed in what's called the "stable phase."  Half of the people in this stage have no notable symptoms, and the disease is detected only because of the elevated count of white blood cells during a normal blood test.

Treatment for CNL usually involves use of the drug we mentioned earlier that was developed after it was discovered how CML was formed.  The drug is Imatinib (or Gleevec).  Put simply, this drug decreases the instance of abnormal effects of the bad gene (the "Philadelphia chromosome").  It also sometimes causes direct death for this bad gene.  As long as the patient is able to handle the drug's side effects, and as long as the disease responds to the drug, he can continue taking it.  And in fact, if the patient stops taking the drug, he is at high risk of the abnormality returning.  A doctor must monitor the Philadelphia chromosome every three or four months while taking the drug.

Newer drugs being used with CML are Dasatinib and Nilotinib.  These are sometimes recommended for patients whose bodies have adapted and started to resist Imatinib.  As with Imatinib, these drugs must be taken regularly, or else the patient is at risk of having the abnormal chromosome return.  And again, the use of the drug, and the presence of the Philadelphia chromosome, must be regularly monitored for several months when taking these drugs.  For more information about any of these options, speak to your physician.