Acute Myeloid Leukemia (AML) is a rapidly progressing cancer that originates in the blood and bone marrow. It is characterized by the uncontrolled proliferation of abnormal, immature white blood cells called myeloblasts, which crowd out healthy cells. AML does not use a traditional numerical staging system, such as Stage I or Stage IV. Instead, the patient journey is understood through distinct treatment phases: diagnosis and classification, initial treatment, post-remission therapy, and disease recurrence.
Understanding AML Classification
Since AML does not use conventional staging, doctors rely on detailed classification systems to understand the disease’s biology and guide treatment decisions. The older French-American-British (FAB) system categorized AML into subtypes M0 through M7 based on the physical appearance of the leukemia cells under a microscope.
The current standard is the World Health Organization (WHO) classification, which provides a more meaningful prognostic picture by incorporating genetic and molecular findings. The WHO system groups AML by the presence of specific chromosomal abnormalities and gene mutations, such as the $RUNX1-RUNX1T1$ fusion or the $PML-RARA$ translocation, which are associated with different outcomes. This genetic-based classification is fundamental because it directly informs the choice of therapy, as certain molecular markers can be targeted with specific drugs.
The First Phase: Induction and Remission
The initial and most aggressive treatment is called Induction Therapy, focused on rapidly clearing the bulk of the leukemia cells. The primary goal is to achieve a Complete Remission (CR), which signifies the restoration of normal blood cell counts and the reduction of myeloblasts in the bone marrow to less than 5%. This intensive regimen typically involves combination chemotherapy, often the “7+3” protocol (cytarabine for seven days and an anthracycline for three days).
The induction phase is generally a short, intense period, often requiring a hospital stay while the patient recovers from the chemotherapy effects. For many patients, induction chemotherapy results in remission, though some may require a second round of therapy to achieve this status.
Sustaining Progress: Consolidation and Maintenance
Achieving complete remission begins the post-remission treatment, which is essential to prevent the disease from returning. Consolidation Therapy is the next intensive step, designed to eradicate any residual leukemia cells that survived induction. Without consolidation, most patients who achieve remission would experience a relapse within months.
This phase often involves several cycles of high-dose chemotherapy, most commonly high-dose cytarabine (HiDAC). For patients with intermediate or adverse-risk AML, allogeneic stem cell transplantation may be used as the consolidation treatment, offering a higher chance of long-term remission. Following consolidation, some patients may receive Maintenance Therapy, which uses less intensive, long-term medication to further lower the risk of recurrence.
Disease Recurrence: Relapsed and Refractory AML
AML can sometimes return, known as Relapsed AML, meaning the disease has recurred after a period of complete remission. Refractory AML applies to cases where the leukemia fails to achieve a complete remission despite induction chemotherapy.
Both relapsed and refractory states require a distinct and more complex treatment approach, as the leukemia has demonstrated resistance to initial therapies. Treatment often involves intensive salvage chemotherapy regimens, targeted therapies that exploit specific genetic mutations, or second allogeneic stem cell transplants. The goal is to achieve another complete remission, which may then be followed by a transplant to sustain the response.