Cancer starts when cells in the body change (mutate) and grow out of control. Your body is made up of tiny building blocks called cells. Normal cells grow when your body needs them, and die when your body doesn't need them. Cancer cells grow even though your body doesn’t need them. In most types of cancer, the abnormal cells grow to form a lump or mass called a tumor.
Leukemia is different from most other types of cancer. Leukemia is cancer that starts in the bone marrow. This is where new blood cells are made. The bone marrow is a thick, sponge-like tissue in the center of certain bones in your body.
Leukemia cells are early or immature forms of blood cells, most often white blood cells. When a person has leukemia, the body makes too many abnormal blood cells. These cells don't work the way they should and don't mature into functional cells.
Leukemia cells seldom form tumors, but they can travel with the blood all over the body. This means leukemia can affect organs all over the body.
Two types of white blood cells can turn into leukemia:
Lymphoid cells (lymphocytes). This is called lymphocytic or lymphoblastic leukemia.
Myeloid cells (myelocytes). This is called myeloid or myelogenous leukemia.
Leukemia can also be either acute or chronic. Acute leukemia tends to grow very quickly and needs to be treated right away. Chronic leukemia often grows more slowly. It may take a long time before treatment is needed.
Acute myeloid leukemia (AML) is a type of leukemia that starts in very early or immature forms of white blood cells called myeloblasts (or blasts for short). It’s also known as acute myelogenous leukemia. In some cases, the leukemia cells start in early red blood cells called megakaryocytes.
As the leukemia cells grow, they crowd out the normal cells in the bone marrow. This can keep the bone marrow from making enough of different types of healthy blood cells.
People with AML have too many white blood cells in their blood. But these cells are not normal and don't help fight infections. In fact, people with AML often get more infections than people without it. AML can also lead to low blood cell levels. This is called anemia. It can cause paleness, shortness of breath, and tiredness (fatigue). AML can lead to not enough platelets, too. This can cause easy bleeding or bruising.
AML is a type of acute leukemia. This means it tends to grow fast. It needs to be treated right away.
AML comes in many subtypes. They are based on the exact type of cells the leukemia starts in and how mature the cells are. Which subtype of AML you have can affect both your treatment and prognosis (outlook). The main classification system of subtypes is the French-American-British or FAB system:
M0. This is undifferentiated AML.
M1. This is AML with few or no mature cells.
M2. This is AML with mature cells.
M3. This is acute promyelocytic leukemia (APL).
M4. This is acute myelomonocytic leukemia (AMML).
M4eo. This is AMML with a type of red blood cell called eosinophils.
M5. This is acute monocytic leukemia.
M6. This is acute erythroid leukemia.
M7. This is acute megakaryoblastic leukemia (AMKL).
AML may be broken down into other subtypes with a different system than this one. Ask your healthcare provider which system he or she is using and what it means for you. The subtype of AML may determine which treatment is best for you.
Another way to classify AML is by looking for certain genetic changes in the leukemia cells. These changes help your healthcare provider decide on the best treatment plan. They also help your provider know what your likely outlook is. Some gene changes are better (called favorable abnormalities) than others (unfavorable abnormalities).
If you have questions about your AML, talk with your healthcare provider. Your healthcare provider can help you understand more about the exact type of leukemia you have.