Chronic myelogenous leukemia (CML), also called chronic myeloid leukemia or chronic granulocytic leukemia, is a type of cancer that develops from the bone marrow. It is a rare type of cancer that results in high numbers of white blood cells that compromises their healthy function. In contrast with acute myelogenous leukemia (AML), CML progresses slower. However, they both refer to the myeloid type of cells found in the bone marrow. It can affect all group ages but is more prevalent among older adults. CML is manageable, and patients may maintain a good quality of life for several years.
The four main types of leukemia
Leukemia may present acutely or chronically, and it may involve the myeloid or the lymphoblastic cells of the bone marrow. To differentiate between its types, scientists classify the disease as follows:
- Acute myelogenous leukemia (AML)
- Chronic myelogenous leukemia (CML)
- Acute lymphocytic leukemia (ALL)
- Chronic lymphocytic leukemia (CLL)
How common is chronic myelogenous leukemia?
CML is a rare disease that mainly affects older adults. An estimated 8,450 people will present with CML in 2020 in the US, and about 1,130 individuals will die from it. The disease is slightly more common in men than in women. CML represents about 15% of all cases of leukemia, and the average age of diagnosis is 64 years. There is no available data regarding the five-year survival rate of CML. In 2001, scientists introduced the most effective drugs against CML. However, most patients diagnosed in 2001 are still alive. A study involving the drug imatinib suggests that the five-year survival rate of people with CML is about 90%.
What is the cause of chronic myelogenous leukemia?
Scientists know the mechanism by which CML develops and progresses. However, it is not clear what causes it. For years, doctors suggest that cancer is the result of mutations or changes in the DNA of some cells that they finally become cancerous. Malignant cells grow fast and can invade other tissues which are adjacent or distant to the primary cancer site. Scientists also noticed that the Philadelphia gene is present in almost 90% of patients with CML.
What are the risk factors of chronic myelogenous leukemia?
Risk factors increase an individual’s chance of developing a disease. The following are some of the most well-established risk factors for CML:
- Age. Being older increases your risk of developing CML. The average age of presenting with the disease is 64 years old.
- Sex. Being a man raises your chances of developing CML in the future.
- Exposure to radiation. Radiation exposure might increase your risk of developing some types of CML.
Symptoms and signs of chronic myelogenous leukemia
CML is usually asymptomatic. Most people receive a diagnosis after a routine blood exam. However, when symptoms and signs present, they might be some of the following:
- Pain in the bones
- Easy bruising or bleeding
- Early satiety, or having the sensation of being full after eating a small portion of food
- Fatigue or exhaustion
- Fever and excessive night sweats
- Unexplained weight loss
- Loss of appetite
- Pain or fullness on the left side of the abdomen
Quick facts about chronic myelogenous leukemia
- CML mainly affects older adults, between 40 and 70 years old
- Family history is not a risk factor for CML
- CML might not cause any symptoms, especially in its initial stage
- CML is mostly treatable due to advances in medicine and technology
- Philadelphia gene is present in almost 90% of patients with CML
- CML has a favorable overall prognosis
- CML is not a common type of leukemia
What are the three stages of chronic myelogenous leukemia?
CML typically presents with the three following stages:
- Chronic phase. This phase represents the first months or years of the disease, during which it progresses very slowly.
- Accelerated phase. During this phase, cancer progresses faster, symptoms and signs worsen, and treatment is not effective.
- Blast phase: During this phase, blast cells develop, leading to severe and life-threatening complications.
Diagnosis of chronic myelogenous leukemia
The following are the tests and procedures used to diagnose CML:
- History taking. Your doctor will start by asking questions to see if you have any risk factors or any other diseases. He or she will also ask you about your symptoms.
- Physical examination. During the physical exam, your doctor will examine you and look for signs of the disease. He or she may palpate your lymph nodes and abdomen, as well.
- Blood exam. The blood test is crucial for the diagnosis of CML, as most people receive a diagnosis after a casual full blood count.
- Bone marrow biopsy. A bone marrow biopsy will allow the doctor to look at your tissue sample under the microscope and confirm the diagnosis.
- Bone marrow aspiration. A bone marrow aspiration has a similar diagnostic value as the biopsy.
- Genetic testing. Genetic testing will reveal the presence or absence of the Philadelphia chromosome.
- Imaging tests. Imaging tests will help stage the disease and look for metastases.
What is the treatment of chronic myelogenous leukemia?
Most people achieve complete remission of CML with targeted treatment whose goal is to eliminate all the cells that contain the BCR-ABL gene. It includes the following drugs:
- Imatinib (Gleevec)
- Dasatinib (Sprycel)
- Nilotinib (Tasigna)
- Bosutinib (Bosulif)
- Ponatinib (Iclusig)
Other treatments include chemotherapy and bone marrow transplant. Chemotherapy uses oral or intravenous drugs to kill cancer cells. A bone marrow transplant could be a definitive treatment for some. Doctors usually combine it with chemotherapy.