Acute Myeloid Leukemia (AML) is a rapidly progressing type of cancer that affects the blood and bone marrow. It starts when certain blood-forming cells in the bone marrow develop genetic changes. These changes lead to the uncontrolled growth of abnormal cells, interfering with the body’s ability to produce healthy blood cells.
Understanding Acute Myeloid Leukemia
AML originates in the bone marrow, where blood cells are made. It impacts myeloid cells, which are immature blood cells that normally mature into various types of white blood cells, red blood cells, and platelets. In AML, these myeloid cells, often called myeloblasts or blasts, do not mature properly and multiply uncontrollably. This accumulation of abnormal cells crowds out the healthy blood-forming cells.
AML: A Different Approach to Classification
Unlike many solid tumors, such as breast or lung cancer, which are assigned numerical stages based on tumor size, spread to lymph nodes, and metastasis, AML is not typically staged in the same way. This is because AML is a cancer of the blood and bone marrow, making it a systemic disease from its onset. The abnormal cells quickly move from the bone marrow into the bloodstream and can potentially spread to other parts of the body, including lymph nodes, the liver, and the spleen. Therefore, a traditional staging system that relies on localized tumor assessment is not applicable to AML.
Key Classification Systems for AML
Instead of staging, AML is classified using systems that focus on the specific characteristics of the leukemia cells, including their morphology and genetic abnormalities. The World Health Organization (WHO) classification system is the primary method used today. This system categorizes AML based on factors such as the percentage of blast cells in the bone marrow or blood, and more importantly, the presence of specific genetic mutations or chromosomal changes within the leukemia cells. For example, certain recurrent genetic abnormalities define distinct AML subtypes. These detailed classifications are important for determining a patient’s prognosis and for guiding the most effective treatment strategies.
Phases of AML Disease Progression
While AML is not assigned traditional stages, patients do experience distinct phases throughout their disease journey. The initial phase is the diagnosis, where the presence of abnormal myeloid cells is confirmed through bone marrow biopsies and blood tests. Following treatment, patients may enter remission, a phase where the leukemia cells are no longer detectable in the bone marrow or blood. However, AML can sometimes return, leading to a phase known as relapse, or it may not respond to initial treatment, which is termed refractory disease. These phases describe the patient’s status and the disease’s response to therapy, rather than a progression through fixed anatomical stages.