Understanding Chronic Myeloid Leukemia (CML)
- Chronic myeloid leukemia (CML) is a type of blood cancer that affects the production of granulocytes (a kind of white blood cell) from the bone marrow.
- If you have chronic myeloid leukemia— your body will produce abnormal granulocytes (also called blasts) in large numbers which may subsequently lead to infections, anemia, and easy bleeding. With CML, the bone marrow is making too many white blood cells.
- Patients with chronic myeloid leukemia (CML) usually don’t exhibit any symptoms in the early stages. As the disease progresses, they may experience loss of appetite, fatigue, night sweats, headaches, frequent infections, and bone pain, among others.
- Targeted therapy, chemotherapy, and bone marrow transplantation are the current treatment options available for CML.
Normally, the BCR-ABL1 gene is absent in healthy people, but in patients with chronic myeloid leukemia (CML), this gene is produced from a cell division error (translocation) between chromosomes 9 and 22 (Philadelphia chromosome) and in turn, produces the BCR-ABL1 tyrosine kinase protein that leads to the development and accumulation of chronic myeloid leukemia (CML) cells and brings about symptoms of the disease.
Causes and Risk Factors of Chronic Myeloid Leukemia (CML)Read More
Thus, chronic myeloid leukemia (CML) is an acquired disease from a gene mutation and is neither inherited (passed down from generation to generation) nor contagious. Although the reason behind this mutation remains unknown, some scientific data support that the following risk factors may increase your chances of getting chronic myeloid leukemia (CML), these include the following:
- Age — the older you are, the higher your chances
- Gender — Men are more susceptible to CML
- Exposure to radiation
Symptoms of Chronic Myeloid Leukemia (CML)
Usually, chronic myeloid leukemia (CML) doesn’t produce any symptoms in the early stages. As the disease progresses, patients may experience any of the following symptoms:
- Fatigue or tiredness
- Night sweats
- Unexplained weight loss
- High fever
- Pain on the left side below the ribs
- Loss of appetite
- Bone pain
- Bleeding easily
- Getting full quickly when eating
- Shortness of breath
- Pale skin
- Frequent infections
These signs and symptoms are mostly dependent on which stage of the disease the patient is in.
Stages of Myeloid Leukemia (CML)
If you have chronic myeloid leukemia— your body will produce abnormal granulocytes (also called blasts) in large numbers which may subsequently lead to infections, anemia, and easy bleeding. With CML, the bone marrow is making too many white blood cells.
Chronic myeloid leukemia is generally slow-growing cancer that may advance gradually over weeks or even months. It’s classified into three stages; these include the following:
Chronic Phase. In this phase, the percentage of blast cells and blood count remains relatively stable (below 5%) and there are no worrying symptoms which give patients an excellent chance of recovery.
Left untreated, patients will eventually progress to the accelerated or blast phase. However, this can take years to happen.
Accelerated Phase. In this phase, symptoms like night sweats, fatigue, weight loss, and frequent infections start to manifest more clearly as the number of blast cells starts to increase.
This stage can take from three to nine months. Similarly, if left untreated patients will progress to the blast phase.
Blast Phase. This is the last phase of chronic myeloid leukemia, in it, the number of blast cells has dramatically increased, and leukemia has become more aggressive with noticeable symptoms. This phase is also called the ‘blast crisis’.
Even though chronic myeloid leukemia is a slow-growing disease it can evolve into fast-growing acute leukemia. Unfortunately, at the blast phase if patients aren’t treated it’s most probably fatal.
Evidently, most patients (about 90%) are diagnosed with chronic myeloid leukemia at the chronic phase when there are no significantly noticeable symptoms through routine checkups and abnormal blood work.
Diagnosis of Chronic Myeloid Leukemia (CML)
Below is a list of the diagnostic tests for chronic myeloid leukemia (CML), your doctor will prescribe any of the following tests as they see fit:
- Medical history
- Physical examination
- Complete blood count (CBC) with differential — to measure the number of red blood cells, white blood cells, and platelets. Also, to determine the amount of hemoglobin in your blood, the percentage of red blood cells (hematocrit), and the type of white blood cells in your blood.
- Peripheral blood smear — In this test, your blood cells will be dyed and examined under the microscope to compare the proportion of blast cells to normal cells, identify a specific pattern of white blood cells, and determine the number, size, and shape of white blood cells.
- Bone marrow biopsy or aspiration — After the blood tests show positive results for chronic myeloid leukemia, your doctor may prescribe a bone marrow test to confirm the diagnosis. The idea behind this test is to examine bone marrow cells and look for chromosomal changes under a microscope. For a bone marrow biopsy, a wide needle is used to remove a piece of the bone marrow. But for a bone marrow aspiration, a small needle is inserted into the bone marrow to remove a liquid sample for examination.
- Genetic testing — using specialized techniques like the fluorescence in situ hybridization (FISH) analysis and the polymerase chain reaction (PCR) test to look for the presence of chromosomal abnormalities or gene mutations like the Philadelphia chromosome or BCR-ABL gene.
Treatment Options for Chronic Myeloid Leukemia (CML)
Dr. Adrienne Philips, a Hematologist/Medical Oncologist, at Weill-Cornell Medicine, says, “If you have CML, you’re going to be on a therapy that targets the Philadelphia chromosome”.
To treat chronic myeloid leukemia, you have three main options, and include the following:
- Targeted therapy — where drugs will be used that target specific proteins or genes of cancer to eliminate it (ex. tyrosine kinase inhibitors (TKIs).
- Chemotherapy — drugs that carry toxic substances that inhibit the cancer cells. These are mostly used when TKIs aren’t effective, or they cause intolerable side effects. (ex. hydroxycarbamide).
- Bone marrow transplantation or stem cell transplantation — where healthy immature blood cells (stem cells) replace abnormal cancer cells. When it works it can be curative. However, this procedure carries a lot of risks.
Treatment for CML will depend on what stage of the disease a person is diagnosed at. There are a handful of symptoms associated with this particular type of cancer, but unfortunately, they can be nonspecific and are linked to several other ailments—as well as other types of cancer.
In the early phases of the disease (chronic/early stage), CML is often treated with a type of drug called tyrosine kinase inhibitors (TKIs). These kill the abnormal CML cells in the blood and can control the disease for years.
Dr. Ghaith Abu-Zeinah, an instructor in Medicine at Weill Cornell Medical College and an Assistant Attending Physician at the New York-Presbyterian Hospital, explains, “there has been a revolution of the newer generation of tyrosine kinase inhibitors, developed to use in the long-term treatment of CML”.
When a person is diagnosed at a later stage, they can also be treated with TKIs. For patients who are not responding appropriately to TKI therapy, there is the possibility of using a type of immunotherapy called interferon alfa or receiving a bone marrow transplant or a type of immunotherapy called interferon alfa. Your doctor may also suggest a combination of therapies.
People who are diagnosed in the “blast” phase typically experience a disease that behaves more like acute leukemia. Unfortunately, the treatment options are limited. There is some potential for TKIs in this phase as well, and some patients may be able to try a stem cell transplant. Most patients with this type of CML cannot be cured, so doctors may suggest a palliative care (reducing symptoms rather than curing the disease) approach instead.
Nevertheless, it’s important to note that all these treatments have their share of side effects. Therefore, you should discuss with your doctor the risks and benefits of each treatment option and reach an agreement on the best course of treatment suitable for you.
The Bottom Line
Chronic myeloid leukemia that is BCR-ABL1 positive is a type of myeloproliferative neoplasm (MPN). With CML, the bone marrow is making too many white blood cells. CML is generally slow-growing cancer, but it can evolve into fast-growing acute leukemia. Moreover, early diagnosis is key to achieving excellent treatment response results.
Moving Forward – Questions to Ask Your Doctor
- What tests need to be performed to diagnose my condition?
- What treatment options are available for me?
- If I do not have any symptoms, do I need to be started on medication?
- Should I get a second option regarding my diagnosis?
- What clinical trials are available that I may participate in for new drug therapies?