Status of acute leukemia after treatment

How well acute leukemia (ALL or AML) responds to the first (induction) treatment has an effect on long-term outlook.

A remission or complete remission is usually defined as showing no leukemia after the 4 to 6 weeks of induction treatment. This means the bone marrow has fewer than 5% blast cells, the blood cell counts are normal, and there are no signs or symptoms of the disease. A molecular complete remission means there is no evidence of leukemia cells in the bone marrow, even when using very sensitive lab tests. Even when leukemia is in remission, this does not always mean that it has been cured.

Minimal residual disease (MRD) is a term used after treatment when leukemia cells can't be found in the bone marrow using standard lab tests (such as looking at cells under a microscope), but more sensitive tests find that leukemia cells are still in the bone marrow. Children with MRD during or after induction are more likely to have their leukemia come back and may require more intense treatment.

Active disease means that either the leukemia is still present during treatment or that the disease has relapsed (come back) after treatment. For a patient to be in relapse, more than 5% of the marrow must be made up of blast cells.