Acute myeloid leukemia stages
Fact-checked by There is no standardized staging system for acute myeloid leukemia (AML). Instead of AML stages, the blood cancer is classified by factors such as disease subtype and genetics or responses to treatment.
What are the different stages of AML?
Unlike many other cancers, AML does not have a numerical staging system.
Most cancers that form solid tumors are staged on a scale from 0 or 1 to 4, based on the size and spread of the tumors. AML and other leukemias typically do not form solid tumors, so there is no equivalent leukemia staging system.
How AML is classified instead of staged
Instead of measuring what stage AML is in, healthcare providers use other systems to classify the disease:
- Disease subtypes and genetic features: classifies AML based on genetic and molecular characteristics of the cancer
- Disease status and treatment responses: classifies AML based on where someone is in the treatment process, and how their cancer is changing in response to treatment
During an AML diagnosis, doctors order various tests of the blood and bone marrow to identify and count cancerous leukemia cells — a type of immature blood cell called blasts — and characterize them based on their genetic features. The same tests may be repeated regularly to track how the disease changes over time.
These classifications help doctors understand a person’s long-term prognosis and how their cancer needs to be treated.
AML subtypes and defining genetic features
AML subtypes are classified according to the World Health Organization (WHO) criteria, the International Consensus Criteria (ICC), or a combination of both. These diagnostic systems largely classify AML based on defining cellular and genetic features.
WHO criteria
The WHO criteria include three broad categories:
- AML with defining genetic abnormalities: Subtypes are grouped based on which alterations in genes or chromosomes — the structures that cells use to package DNA — are present.
- AML defined by differentiation: Subtypes are grouped based on the degree of blast cell maturity and the specific type of blood cell they are turning into; typically only used when no defining genetic abnormalities are found.
- Secondary myeloid neoplasms: AML arises related to inherited genetic mutations or exposure to a prior cancer therapy.
To receive a diagnosis of AML defined by differentiation, doctors must find that at least 20% of cells in bone marrow or blood are blasts. There is no minimum threshold for most genetic subtypes.
ICC
Like the WHO criteria, the ICC subtype classification is mainly based on which genetic factors are present. In most cases, there is a 10% blast threshold for an AML diagnosis when gene or chromosome abnormalities are present, although some have a 20% threshold.
If someone doesn’t meet requirements for any of the other subtypes but meets the 20% blast threshold, they usually receive a diagnosis of AML not otherwise specified. AML may also be classified as myeloid sarcoma if the cancer forms tumor-like clumps.
Doctors may add a qualifier to the subtype if an individual has inherited genetic mutations that predispose them to AML, has previously been exposed to other cancer therapies, or has a history of certain other blood disorders.
Genetic risk stratification
Based on data from people with different AML genetic abnormalities, the European Leukemia Network (ELN) developed a risk-based classification system to help predict a person’s prognosis at diagnosis.
These define three broad AML risk groups — favorable, intermediate, or adverse — depending on the typical outcomes for someone with a given genetic change who receives intensive chemotherapy. An addition to the ELN classification system defines a slightly different set of AML risk groups for people who receive lower-intensity treatments.
AML classification by treatment status and response
Doctors often classify AML based on the stage of treatment and how a person has responded to that treatment. This includes the following:
- Untreated: This is newly diagnosed AML that has not yet been treated.
- Active: There is detectable disease during or after treatment.
- Remission: Signs and symptoms of AML are reduced or undetectable after treatment.
- Relapsed: Signs of AML return after a period of remission.
- Refractory: AML does not reach remission after initial treatment.
These classifications help doctors better understand how the cancer should be treated. The goal of treatment is to move someone from an active stage of cancer to AML remission, where cancer activity is fully or partially reduced. When standard tests show no evidence of residual cancer, someone is in complete remission. This is not the same as a cure, because the cancer can still return.
Even in complete remission, very sensitive specialized tests can find small amounts of leukemia that remain in the body, called measurable residual disease (MRD). Testing positive for MRD can increase the chances that a person’s cancer will eventually come back.
Relapsed AML, also called recurrent AML, is a return of the disease after a period of remission, which may require additional rounds of treatment. Relapsed AML typically has a poorer prognosis than newly diagnosed AML, although the disease can still go back into remission.
In refractory AML, the disease doesn’t respond to initial treatment, and alternative therapies may be needed.
What people may mean by ‘advanced AML’ or ‘stage 4 AML’
Although stage 4 AML is not standard medical terminology, people may use the phrase to refer to the final stages of the disease.
During this period, also known as advanced AML, the bone marrow can no longer produce the blood cells the body needs to function. Patients may experience severe symptoms and, eventually, organ failure.
In the final stages of AML, the cancer has stopped responding to treatment. At this point, the main goal is to make patients as comfortable as possible. This is achieved through palliative care, a branch of medicine that focuses on comfort and quality of life. Hospice care is a specialized type of palliative care that focuses on the end-of-life period.
Rare Cancer News is strictly a news and information website about the disease. It does not provide medical advice, diagnosis, or treatment. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read on this website.
