Types of Acute Myeloid Leukemia (AML)

One system that can be used to classify AML is the French-American-British (FAB) system. There are nine subtypes of AML in the FAB system. They are called M0 through M7, with two M4 subtypes. The subtypes are based on the type of cell from which the leukemia developed and how mature the cells are. This is based largely on how the leukemia cells look under the microscope. This system gives some sense of your prognosis, so you can talk with your doctor about it. But there are other prognostic factors that can affect your outlook as well, such as your age and chromosome and gene changes in the leukemia cells.

M0 (Undifferentiated AML). About 5 percent of people with AML have this subtype. The prognosis is worse than average.

M1 (Myeloblastic leukemia with minimal maturation). About 15 percent of people with AML have this subtype. The prognosis is average.

M2 (Myeloblastic leukemia with maturation. About 25 percent of people with AML have this subtype. The prognosis is better than for most other types of AML.

M3 (Promyelocytic leukemia). About 10 percent of people with AML have this subtype. It has the best prognosis of all the AML subtypes.

M4 (Myelomonocytic leukemia). About 20 percent of people with AML have this subtype. The prognosis is average.

M4eo (Myelomonocytic leukemia with eosinophilia). About 5 percent of people with AML have this subtype. The prognosis is better than average.

M5 (Monocytic leukemia). About 10 percent of people with AML have this subtype. The prognosis is average.

M6 (Erythroid leukemia). About 5 percent of people with AML have this subtype. The prognosis is worse than average.

M7 (Megakaryoblastic leukemia). About 5 percent of people with AML have this subtype. The prognosis is worse than average.

A newer, slightly more complicated system for classifying AML has been developed by the World Health Organization (WHO). Along with the cell type and maturity of the cells, this system takes into account other factors, such as chromosome changes in the cells and whether or not the leukemia is the result of previous cancer treatments. Not all doctors may be using the WHO system yet, so ask your doctor which system he or she is using and what it means in your case.