Chronic Myelogenous Leukemia: What You Need to Know
It's natural to be worried about your diagnosis of chronic myelogenous leukemia. But the more you can learn about CML, the more in control of your condition you'll feel.
What is CML?
Chronic myelogenous leukemia (also called chronic myeloid leukemia or CML) is a type of cancer that affects blood cells and bone marrow, the spongy tissue inside bones where blood cells are produced.
The name "myelogenous" comes from myelocyte, a kind of immature white blood cell. White blood cells are the immune system cells that help your body fight infection. CML has three phases: chronic, accelerated, and blastic.
When you have chronic phase CML, you're in the earliest phase of the disease. You might not even realize that you have CML until you're diagnosed. Many people in this phase of CML do not have any symptoms.
In the accelerated phase, the number of abnormal blood cells in your body increases. People in this phase usually have symptoms such as:
- Night sweats
- Shortness of breath
- Unexplained weight loss
- Appetite loss
- Swelling or pain on your left side (which could be a sign of an enlarged spleen)
- Bone pain
Other side effects may include stroke, visual changes, ringing in the ears, stupor, and prolonged erections (priapism).
When CML reaches the blastic phase, the abnormal cells have multiplied to the point where they're crowding out healthy white blood cells, red blood cells, and platelets. People who are in the blastic phase experience more severe symptoms, including infections, bleeding, skin lesions, swollen glands, and bone pain. This is the most serious phase of CML.
Your doctor will use medication or other treatments to keep your CML in the chronic phase, when it's easiest to treat.
What Causes CML?
CML starts in your genes. Each human cell contains structures called chromosomes, which carry the genes (DNA). Genes are the codes that instruct cells to produce certain proteins.
For some reason (which researchers haven't yet pinpointed), in CML, a section of chromosome 9 switches places with a section of chromosome 22. The combination produces a new chromosome, called the Philadelphia chromosome (named after the city where it was discovered).
The Philadelphia chromosome creates a new gene, called BCR-ABL. This gene instructs blood cells to produce a protein called tyrosine kinase.
Tyrosine kinase causes your body to make too many white blood cells. These white blood cells are immature. They don't work as well as normal white blood cells. As a result, your body can't fight infection as well as it used to. The extra abnormal white blood cells leave less room for healthy white blood cells, red blood cells, and platelets.
Learning That You Have CML
You might have no idea you have CML until your doctor discovers it during a routine blood test. About half of people who are diagnosed with chronic phase CML don't have any symptoms.
If your doctor suspects that you have chronic phase CML, tests can be done to confirm the diagnosis. These tests include:
- A complete blood count (CBC) to determine how many white blood cells, red blood cells, and platelets you have
- Bone marrow aspiration and biopsy, in which a sample of bone marrow and blood are examined to determine how advanced the cancer is
- Fluorescence in situ hybridization (FISH) to measure the number of cells containing the Philadelphia chromosome
- CT scans to evaluate the size of your spleen
- Polymerase chain reaction (PCR) looks for the BCR-ABL cancer gene in your cells.