Acute Promyelocytic Leukemia (APL)

What is acute promyelocytic leukemia?

In acute promyelocytic leukemia (APL), the bone marrow produces too many cells called promyelocytes. When too many promyelocytes gather in the marrow, they crowd out healthy blood cells. If there are not enough healthy blood cells to do their jobs, patients are at high risk for infection or bleeding.

APL is a subtype of the cancer acute myeloid leukemia (AML). About 4 to 8 percent of all childhood AML is acute promyelocytic leukemia.

How common is acute promyelocytic leukemia?

Around 1 percent of all childhood leukemias are APL, which is most often diagnosed in children of Hispanic or Mediterranean descent. It is very rare in children younger than 3. The average age of diagnosis is 8 to 10 years. An APL diagnosis should be considered a medical emergency. If you have been told that your child may have APL, the child needs medical attention right away.

What are the symptoms of acute promyelocytic leukemia?

If your child has APL, the following symptoms may be present:

• Bleeding that is hard to stop, even from a small cut
• Blood in the urine
• Heavy nosebleeds
• Bleeding gums and easy bruising
• Fever and infections
• Low red blood cell count
• Paleness
• Tiring easily
• Poor appetite
• Unexplained weight loss

How is acute promyelocytic leukemia treated?

Treatment of APL differs from treatments for other forms of leukemia. Many children with APL require admission to the intensive care unit because of problems that occur when treatment begins.

In general, treatment of APL has three phases:

• Induction. This phase often includes giving all-trans retinoic acid (ATRA), which is similar to vitamin A. It is combined with standard chemotherapy. Future studies plan to use arsenic trioxide during induction for a selected group of patients.
• Consolidation/intensification. In this phase, ATRA, a drug known as arsenic trioxide and chemotherapy are given together. The combination is used to get rid of any cells that may have been inactive during the first phase but could start to grow and cause APL to return (relapse).
• Maintenance. ATRA and chemotherapy are given for about a year to avoid a relapse of APL.

Because this three-phase treatment is usually successful, stem cell transplantation (which helps grow healthy blood-forming cells) is not usually done.

If APL returns, most children can be put into a second remission using arsenic trioxide, alone or combined with chemotherapy and stem cell transplantation.

What is the survival rate for acute promyelocytic leukemia?

At least 85–90 percent of children treated for APL are considered cured.

Why choose St. Jude for your child’s acute promyelocytic leukemia treatment?

• St. Jude is the only National Cancer Institute-designated Comprehensive Cancer Center devoted solely to children.
• St. Jude has created more clinical trials for cancer than any other children’s hospital in the United States.
• The nurse-to-patient ratio at St. Jude is unmatched—averaging 1:3 in hematology and oncology, and 1:1 in the Intensive Care Unit.
• The hospital’s leukemia studies have pioneered the way the world treats childhood leukemia.
• The mortality rate during treatment induction of acute myeloid leukemia and acute promyelocytic leukemia is among the lowest in the nation.