Acute Myeloid Leukemia

Posted on 20/07/2016 by admin — No Comments ↓

Acute myeloid leukemia is a malignancy involving the bone marrow. This type of leukemia is the second most usual type found in both children and adults [1, 2].

What is Acute Myeloid Leukemia?

Acute Myeloid Leukemia (AML) is the malignancy that affects the bone marrow and the blood cells. The bone marrow is the soft connective tissue found inside the bones and their main function is the production of different types of blood cells. In AML, the cells of the bone marrow fails to become white blood cells, red blood cells or platelets.

They turn into immature white blood cells called myeloid blasts or myeloblasts. The body has no use for this type of cells so they continue to build up. They will accumulate in the blood and leave little space for normal blood cells to grow and develop. The low count of blood cells may lead to anemia, infection or bleeding [3, 4, 5].

Haematopoeisis at bone marrow acute Myeloid Leukemia

AML can spread to other parts of the body and can be fatal if they are not treated promptly. Organs which may be affected by AML would include the brain, spinal cord, liver, spleen and testicles. The prognosis of this disease depends on factors such as age, history of previous blood disorders and the presence of gene mutations [1, 4, 5].

Subtypes

There are 8 subtypes of AML depending on the features of normal blood cells that may be present along with the myeloblasts. This classification is based on the French, American, British (FAB) system that is utilized by physician. The subtypes M0-M5 begins in early white blood cells, M6 starts in early red blood cells and M7 starts in early platelet cells [1, 4].

AML SUbtypes

Causes

AML is associated with gene mutations and chromosomal changes because they cause the transformation of normal cells of the bone marrow to leukemia cells. Some of these changes are translocation and deletion. Translocation is considered to be the most common change in the DNA which can cause leukemia. In this event, a segment of a chromosome breaks and attaches to another chromosome. The point where the break occurred may affect nearby genes. In deletion, a part of the chromosome is lost and may result to the loss of the gene’s ability to regulate its own growth [6].

Risk Factors

There are also risk factors which may increase the likelihood of having AML. Some of these factors include smoking, exposure to high levels of radiation and chemicals such as paint strippers, detergents and benzene. A person who underwent chemotherapy for a different type of cancer may also develop AML later in his life. The presence of other disorders such as blood disorders and congenital syndromes can also be a risk factor [4].

Signs and Symptoms

The symptoms that an individual experiences depend on the blood cells that have decreased. Low red blood cells may lead to light-headedness, dizziness, feeling cold and shortness of breath. Shortage of functioning white blood cells can cause fevers and recurrent infections. Those with AML that has low numbers of platelets may experience frequent bleeding in the nose and gums and the appearance of lots of bruises [1, 4, 6]. Figure 1 shows the bruises associated with AML.

AML Symptoms

Figure 3 – Bruises associated with AML

Aside from these, other symptoms that may be experienced include development of lumps in the skin, enlarging lymph nodes especially in the neck area or under arms, pain in the joints, swollen belly due to the accumulation of myeloblasts in the liver and spleen, seizures, vomiting and blurred vision [1, 4, 6].

Diagnosis

Health history and physical examination

A patient will usually consult a physician due to the presence of the aforementioned symptoms. The physician will note the time when they started appearing and if they have worsen over time. The physical examination will include an assessment of the body to identify other symptoms which may have been present [7].

Blood tests

If AML is suspected, a blood count may be performed. This tests will not only reveal the lack of blood cells but will also show the presence of blasts cells. These immature blood cells are normally seen in the bone marrow and not in the circulatory system. The presence of these cells in the blood is an indicator of the presence of AML [7].

Bone marrow test

Although a blood test may suggest AML, a biopsy of the bone marrow is considered to be the confirmatory test for AML. In this procedure, a sample of the bone marrow will be obtained and tested in the laboratory. The bone marrow is usually obtain from the posterior iliac crest or hipbone [7].

Treatment

The treatment that is used for AML depends on the subtype [2, 4, 5, 7].

Chemotherapy

This treatment utilizes anticancer drugs to eliminate the cancer cells. Chemotherapeutic drugs may also kill normal blood cells while eliminating the cancer cells so patients are admitted in the hospital during this treatment for monitoring. The cycle of treatment can be repeated if the first cycle did not cause a remission [2, 4, 5, 7].

Radiation therapy

Radiation therapy uses high energy beams such as x-rays in eliminating cancer cells. This treatment is not usually used for AML but it is effective in treating the leukemia in the bone, brain or testicles [2, 4, 5, 7].

Bone marrow transplant

A patient who is to undergo a transplant will first receive chemotherapy and radiation therapy before the transplant occurs. The stem-cells that are going to be transplanted may come from a donor or one’s own bone marrow [2, 4, 5, 7].

Prognosis, Life Expectancy and Survival Rate

Age plays a big role in the survival rate of patients with AML. Younger patients are able to respond better with the treatment than older people. The highest 5-year survival rate are seen in patients less than 14 years old which is at 65%. The rate for those who are between 15-24 years old is around 60%. Patients who are aged 65 years old and older when they are diagnosed with AML have a very low survival rate (5%).

Several factors affect the prognosis of the patients. Aside from age, genetic abnormalities in the leukemic cells may make it respond poorly to treatment. The stage of the condition when it is diagnosed in the patient is another factor. The more advanced the stage, the poorer the outlook is. The time when AML reaches remission is also another factor. The longer it takes for AML to reach this stage, the harder it will be to be treated. If the AML had relapsed, the symptoms of a relapsed AML can be managed through chemotherapy.
References

Appelbaum, F. (2015). Acute Myeloid Leukemia. Retrieved from Leukemia and Lymphoma Society: https://www.lls.org/leukemia/acute-myeloid-leukemia
Cancer.Net Editorial Board. (2016, January). Leukemia – Acute Myeloid – AML: Statistics. Retrieved from Cancer.Net: http://www.cancer.net/cancer-types/leukemia-acute-myeloid-aml/statistics
Bailey, R. (2015). Bone Marrow. Retrieved from Biology.about.com: http://biology.about.com/od/anatomy/ss/bone-marrow.htm
Movva, S. (2015, April 26). Acute Myeloid Leukemia. Retrieved from Web MD: http://www.webmd.com/cancer/lymphoma/acute-myeloid-leukemia-symptoms-treatments
National Cancer Institute. (2015, September 17). Adult Acute Myeloid Leukemia Treatment (PDQ®)–Patient Version. Retrieved from National Cancer Institute: http://www.cancer.gov/types/leukemia/patient/adult-aml-treatment-pdq
American Cancer Society . (2016, February 22). Do we know what causes acute myeloid leukemia? Retrieved from American Cancer Society: http://www.cancer.org/cancer/leukemia-acutemyeloidaml/detailedguide/leukemia-acute-myeloid-myelogenous-what-causes
Mayo Clinic Staff. (2015, September 12). Acute myelogenous leukemia (AML). Retrieved from Mayo Clinic: http://www.mayoclinic.org/diseases-conditions/acute-myelogenous-leukemia/basics/treatment/con-20043431