Most types of cancer are assigned a numbered stage based on the size of the tumor and how far it has spread. But because leukemia already involves all 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 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 divide ALL into groups based on certain features of the cells and how mature the leukemia cells are.
The subtypes of ALL are now named as follows:
B-cell ALL
- 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
T-cell ALL
- Pre-T ALL - about 5% to 10% of cases
- Mature T-cell ALL - about 15% to 20% of cases
The subtypes of ALL carry slightly different outlooks, 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.
Prognostic factors
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 they respond 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.
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