Acute lymphoblastic leukemia (ALL) is the most common cancer diagnosed in children. The
cancer comes from a cell in the blood called a lymphocyte. Normal lymphocytes are produced in
the bone marrow (along with other blood cells) and help fight infections. In ALL, the
cancerous lymphocytes are called lymphoblasts. They do not help fight infection and crowd out
the normal blood cells in the bone marrow so that the body cannot make enough normal blood
cells. ALL is always fatal if it is not treated. With current treatments, most children and
adolescents with this disease will be cured.
The standard treatment for ALL involves about 2 years of chemotherapy. The drugs that are
used, and the doses of the drugs, are similar but not identical for all children and
adolescents with ALL. Some children and adolescents receive stronger treatment, especially
during the first several months. A number of factors are used to decide how strong the
treatment should be to give the best chance for cure. These factors are called "risk
factors". This trial is studying the use of a new, updated set of risk factors to decide how
strong the treatment will be. The study also will test a new way of dosing a chemotherapy
drug called pegaspargase (which is part of the standard treatment for ALL) based on checking
levels of the drug in the blood and adjusting the dose based on the levels.