Acute promyelocytic leukemia

APL is caused by a chromosomal translocation (rearrangement of material) that occurs in some of the body's cells during a person's lifetime (a somatic mutation). The translocation involves the fusion of two genes: the PML gene on chromosome 15 and the RARA gene on chromosome 17. The protein produced by this fusion is referred to as PML-RARα. The PML-RARα protein functions differently than what is typically produced by the normal PML and RARA genes. As a result of the abnormal function, blood cells become "stuck" at the promyelocyte stage and they proliferate (reproduce) abnormally. Excess promyelocytes then accumulate in the bone marrow, disrupting the formation of normal white blood cells and leading to APL. Translocations involving the RARA gene and other genes have been identified in only a few cases of APL.

We were unable to locate information about the availability of predictive testing for APL. Predictive genetic testing is primarily an option for individuals at risk for inherited cancers and other inherited disorders; APL is not an inherited cancer. Predictive genetic tests are generally available if a close family member has had a genetic test which has identified a specific mutation that is associated with an inherited predisposition to cancer. APL is caused by a somatic mutation which is acquired during a person's lifetime and is not passed on to children. Furthermore, it is not necessarily known when during a person's lifetime a somatic mutation might occur.

Individuals that are interested in learning more about predictive testing for a particular type of cancer should speak with a genetics professional.

APL is not inherited. The condition arises from a translocation in some of the body's cells (somatic cells) that occurs after conception. This is referred to as a somatic mutation. Somatic mutations may affect the individual by causing cancers or other diseases, but they are not passed on to offspring.

APL accounts for about 5-15% of all adult leukemias. There are approximately 30,800 cases of acute leukemia diagnosed yearly; about 1000 of these are acute promyelocytic leukemia.

Most cases of APL are treated with an anthracycline chemotherapy drug (daunorubicin or idarubicin) plus the non-chemotherapy drug, all-trans-retinoic acid (ATRA), which is a relative of vitamin A. This treatment leads to remission in 80% to 90% of patients.

Patients who cannot tolerate an anthracycline drug may get ATRA plus another drug called arsenic trioxide. Arsenic trioxide has also proven to be an effective alternative for the 20% to 30% of patients with APL who don't respond to initial treatment or who relapse. If treatment with arsenic trioxide achieves a remission, further courses of this drug may be given. A stem cell transplant may also be an option. If a second remission is not achieved, treatment options may include a stem cell transplant or taking part in a clinical trial.

Additional information related to treatment of acute promyelocytic leukemia can be accessed through Medscape. This includes detailed information related to the use of arsenic trioxide.