Unlike acute types of leukemia, chronic myelogenous leukemia is a condition with a gradual progression. It is more commonly seen in middle-aged or older adults [1, 2].
What is Chronic Myelogenous Leukemia?
In This Article
- 1 What is Chronic Myelogenous Leukemia?
- 2 Staging
- 3 Causes
- 4 Signs and Symptoms
- 5 Diagnosis
- 6 Treatment
- 7 Life expectancy
Chronic myelogenous leukemia (CML) is known as a malignancy that affects blood cells and the bone marrow. The bone marrow produce hematopoietic cells that will mature and turn into different types of normal blood cells.
Image 1 – Blood stem cell differentiation
In CML, hematopoietic cells develop into granulocytes. These cells are considered as abnormal and are unable to become into healthy white blood cells. The granulocytes continuously divide and accumulate leaving no space for normal blood cells into the bone marrow. The 5-year survival rate for CML is 70% for men and 75% for women [3, 4].
There are 3 known phases in the progression of CML [4, 5].
The chronic stage is considered as the most stable phase and is characterized by proliferation of granulocytes. Around 90% of all cases of CML are diagnosed during this phase. Symptoms experienced during this phase are mild and not indicative of leukemia. The number of white blood cells and platelets may be elevated [4, 5].
During this phase, immature cells are rapidly proliferating and some cytogenic abnormalities may occur. The spleen may be enlarged at this point and the patient may feel a painful feeling to the left of the stomach. Around 10- 30% of the blood cells in the body are cancer cells at this point [4, 5].
Acute or blast phase
In the last phase, the immature cells have accumulated in the bone marrow and the leukemia have turned into an acute leukemia. The symptoms that will be experienced will be more pronounced and the leukemia cells have already spread to other organs. At this point, more than 30% of the blood cells are leukemia cells [4, 5].
The development of CML is associated with the Philadelphia chromosome. In this event, there is a translocation between the long arms of chromosome 9 and 22 resulting in a shortened chromosome 22. This will cause the bone marrow to produce an enzyme that will make too many hematopoietic stem cells to become white blood cells [2, 4]
Signs and Symptoms
The signs and symptoms that may be experienced depends on the phase of the CML. Those who are in the first phase may not experience general symptoms or may not present with any symptom at all. Example of these symptoms may include easy fatigability, skin pallor, night sweats, fever and loss in appetite and weight. As the condition progresses, the intensity of these symptoms will be more pronounced and some pain or fullness may be felt on the left side of the stomach. When the patient reached the acute phase, the symptoms will become troublesome for the patient and they will start to become unwell [3, 5].
Image 2 – Symptoms of Leukemia
Health history and physical examination
The initial symptoms of CML are unspecific and the physician will need to get more information in order to establish a diagnosis. The time the symptoms started and any changes in its intensity will be asked by the physician. In the physical examination, the presence of other symptoms will be assessed. The lymph nodes, abdomen and spleen will be checked for any abnormalities [1, 3].
Blood tests such as a complete blood count and blood chemistry will be ordered by the physician. This tests will identify the any abnormalities in the number of blood cells and measure organ function [1, 3].
Image 3 – Peripheral Smear Results – Normal Vs Leukemia
Bone marrow aspiration and biopsy
A sample of the patient’s bone marrow will be collected by inserting a hollow needle in either the hipbone or breastbone. Analysis of the sample will be able to show the presence of leukemia cells in the bone marrow [1, 3].
There are several specialized tests that may be done to check for the presence of this chromosomal error. Examples of these tests include polymerase chain reaction tests and fluorescence in situ hybridization (FISH) analysis. The specimen that is used in this tests is either a blood or a bone marrow sample [1, 3].
There are several treatment modalities that are used to treat CML [1, 2, 5].
Anticancer drugs are used in chemotherapy to either eliminate cancer cells or to stop them from dividing further. The method in which these drugs are administered on the body depends on the type and stage of the malignancy [1, 2, 5].
This therapy also utilized drugs but their effects are specific to cancer cells. The normal cells are not harmed in a targeted therapy. Tyrosine kinase inhibitors are the agents that is usually used in the target therapy of CML [1, 2, 5].
Also known as immunotherapy or biotherapy, this therapy uses the patient’s own immune system to eliminate cancer cells. The substances that are either made by the body or synthesized in a laboratory are used to boost the immune system [1, 2, 5].
Chemotherapy with stem cell transplant
High doses of chemotherapeutic drugs will be given to the patient and the hematopoietic cells that were eliminated will be replaced with stem cells that were obtained from a donor. The stem cells will be infused into the body to restore the number of the body’s blood cells [1, 2, 5].
Donor lymphocyte infusion
After receiving a stem cell transplant, lymphocytes from the same donor will be infused to the patient. The lymphocytes will then identify the cancer cells as foreign and launch an attack against them [1, 2, 5].
The patient may undergo a splenectomy or removal of the spleen after it has enlarged [1, 2, 5].
The life expectancy rate of patients diagnosed with chronic myelogenous leukemia have greatly improved with the use of tyrosine kinase inhibitors. Those with CML used to live for 3-7 years after they are diagnosed but with these inhibitors, most patients are able to live out a normal lifespan. Data have shown that the median age for those with CML have lived is 72 years for males and 78 years for females.
Martin, L. J. (2016, April 10). Chronic Myelogenous Leukemia (CML). Retrieved from Web MD: http://www.webmd.com/cancer/lymphoma/cml-need-to-know-first?page=4
National Cancer Institute. (015, September 21). Chronic Myelogenous Leukemia Treatment (PDQ®)–Patient Version. Retrieved from National Cancer Institute: http://www.cancer.gov/types/leukemia/patient/cml-treatment-pdq
Mayo Clinic Staff. (2016, May 26). Chronic myelogenous leukemia. Retrieved from Mayo Clinic: http://www.mayoclinic.org/diseases-conditions/chronic-myelogenous-leukemia/home/ovc-20202048
Besa, E. (2016, April 14). Chronic Myelogenous Leukemia (CML). Retrieved from Medscape: http://emedicine.medscape.com/article/199425-overview
Cancer Research UK. (2015, July 7). Chronic myeloid leukaemia (CML). Retrieved from Cancer Researck UK: http://www.cancerresearchuk.org/about-cancer/type/cml/
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