How is acute lymphocytic leukemia classified?
Most types of cancer are assigned a numbered stage based on the size of the tumor and how far it has spread. But leukemia does not usually form tumors, and it already involves the bone marrow and, in many cases, has also spread to other organs. The outlook for the person with acute lymphocytic leukemia (ALL) depends on other information, such as the subtype of ALL, the age of the patient, and lab test results.
The older French, American, and British (FAB) system to classify ALL was based only on the way the leukemia cells looked under the microscope after routine staining. This system has largely been replaced, as newer lab tests now allow doctors to better classify ALL.
These lab tests provide more detailed information about the subtype of ALL and the patient's outlook. They let doctors divide ALL into groups based on the type of lymphocyte (B cell or T cell) the leukemia cells come from and how mature the leukemia cells are.
The subtypes of ALL are now named as follows:
- Early pre-B ALL (also called pro-B ALL) – about 10% of cases
- Common ALL – about 50% of cases
- Pre-B ALL – about 10% of cases
- Mature B-cell ALL (Burkitt leukemia) – about 4% of cases
- Pre-T ALL – about 5% to 10% of cases
- Mature T-cell ALL – about 15% to 20% of cases
The subtypes of ALL each carry a slightly different outlook, but other factors (like gene changes in the leukemia cells) may also have an impact. Some of these factors are listed in the next section.
As leukemia treatment has improved over the years, research has focused on why some patients have a better chance for cure than others. Certain features of the disease separate patients who are likely to have a good response to treatment from those likely to have a poor response. These are called prognostic factors. These features include the patient's age, white blood cell count, ALL subtype, certain test results, and how the ALL responds to treatment.
The American Cancer Society has detailed information about these subtypes and prognostic factors in a separate document (called Leukemia: Acute Lymphocytic). You can get it by calling our toll-free number or read it on our Web site.
Last Medical Review: 06/25/2012
Last Revised: 01/24/2013
- What Is Leukemia - Acute Lymphocytic (ALL) in Adults?
- Causes, Risk Factors, and Prevention
- Early Detection, Diagnosis, and Staging
- Treating Leukemia - Acute Lymphocytic (ALL) in Adults
- Talking With Your Doctor
- After Treatment
- What`s New in Leukemia - Acute Lymphocytic (ALL) in Adults Research?
- Other Resources and References