Acute myelogenous leukemia (AML) is a rapidly progressing cancer of the blood and bone marrow. The bone marrow is the tissue in our body that makes blood cells. The name of the disease denotes that cancer begins in the myeloid cells. The myeloid cells are premature cells that later on mature and become various types of white and red blood cells or platelets. Generally, we classify leukemias according to their progression and type of cells they affect, to acute or chronic, and myeloid or lymphoid. The acute leukemias develop and progress more rapidly than chronic leukemias. AML begins in the bone marrow, passes into the blood, and may spread to other parts of the body. In this article, we will focus on the risk factors, cause, types, symptoms, diagnosis, and treatment of AML.
How common is acute myelogenous leukemia?
AML affected an estimated 21,450 people in 2019 in the US. Also, about 10,920 died from AML during the past year. The disease is prevalent in both adults and children, but it is more common in adults. Generally speaking, it is the second most common type of leukemia. The mean age of diagnosis in all age groups is 68 years old. The five-year survival rate for individuals older than 20 years old with AML is about 24%. Adults and children less than 20 years old have a 67% five-year survival rate.
Risk factors of acute myelogenous leukemia
Risk factors may increase your chance of developing a disease. The following are some of the most well-known risk factors for AML.
- Older age. The average age of diagnosis for AML is 68 years old. It is unlikely but possible to diagnose the disease in people younger than 45 years old.
- Sex. Men have a higher risk of developing AML than women.
- Previous cancer treatment chemotherapy or radiation therapy may increase your risk of developing AML in the future.
- Radiation exposure. Exposure to very high levels of radiation increases the risk of developing AML. An example is witnessing a nuclear reactor accident.
- Exposure to chemicals. Some chemicals, such as benzene, may increase your chance to develop AML in the future.
- Cigarette smoking. Cigarette smoking contains many dangerous chemicals, including benzene, which increases your risk for AML.
- Blood disorders. People with other blood disorders have a high risk of developing AML.
- Genetic disorders. Some genetic disorders, Down syndrome, for example, may increase your risk of developing AML.
What is the cause of acute myelogenous leukemia?
Scientists don’t know what exactly causes AML. Mutations or changes in the DNA of some cells of the bone marrow affect the production of these cells. As a result, immature cells start dividing and rapidly growing, leading to cancer and crowding out healthy cells. We don’t know what exactly causes these changes, but risk factors play a significant role.
Types of blood cells
We can divide blood cells into three principal types which are the following:
- Red blood cells (RBCs). RBCs are the cells responsible for carrying oxygen from the lungs to the rest of the body, and carbon dioxide from the other tissues back to the lungs.
- White blood cells (WBCs). WBCs are responsible for fighting against various infections.
- Platelets. Platelets are cell fragments that play a principal role in bleeding cessation.
Types of acute myelogenous leukemia
AML has eight different subtypes, which are the following:
- Myeloblastic (M0)
- Myeloblastic (M1)
- Myeloblastic (M2)
- Promyelocytic (M3)
- Myelomonocytic (M4)
- Monocytic (M5)
- Erythroleukemia (M6)
- Megakaryocytic (M7)
Symptoms of acute myelogenous leukemia
Early symptoms and signs of AML are not typical. They may mimic other medical conditions, such as the flu. AML may present with fever and pain in the bones. Other general symptoms may include some of the following:
- Unusual bleeding and easy bruising
- Susceptibility to infections
- Pale skin
- Weight loss
- Night sweats
- Loss of appetite
AML and leukostasis
Leukostasis is a medical emergency that can appear in people with high numbers of leukemia cells. Abnormal leukemic cells are bigger than healthy cells, meaning they have trouble with going through small vessels. Sometimes, they clog up some small vessels leading to oxygen deprivation in the correspondent tissue. Symptoms and signs depend on the area affected and may mimic a stroke. Some of them are the following:
- Unilateral body weakness
- Blurry vision
- Slurred speech
- Sleepiness and confusion
Diagnosis of acute myelogenous leukemia
To diagnose AML, your doctor will ask you questions about your history, symptoms, and potential risk factors, and he or she will perform a physical exam. A blood test is essential as it will show high numbers of WBCs and blasts and low levels of RBCs and platelets, suggesting AML. To confirm the diagnosis, you may undergo a bone marrow biopsy using a needle. Occasionally, the diagnostic procedure requires a spinal tap and genetic testing.
What is the treatment of acute myelogenous leukemia?
Deciding your treatment plan depends on many factors, such as the subtype of AML, your overall health, medical history, and age. Whatever the agent used, the treatment generally consists of the remission induction therapy and consolidation therapy. The remission induction therapy usually uses chemotherapy, which kills cancer cells with oral or intravenous drugs. Other drug therapies include the following:
- Targeted therapy
- Arsenic trioxide
- All-trans retinoic acid (ATRA)
- Bone marrow transplant
Bone marrow transplant is usually useful as consolidation therapy, following chemotherapy or radiation therapy. To receive a bone marrow transplant, you need a compatible donor. You can also receive your cells as a transplant, in case of relapse, provided that you already stored them while in remission.