What is APL and how is it treated?

Alyssa was diagnosed with Acute Promyelocytic leukemia (APL) on Nov 20, 2010. This is a subtype of Acute Myeloblastic leukemia (AML), and is one of the better subtypes to have.  It has a survival rate of over 90%, and can be treated with chemotherapy only (no bone marrow transplant). 

APL differs from the other subtypes in that the leukemia cells have a unique chromosome abnormality known as a 15 - 17 translocation.  This chromosome abnormality makes the leukemia cells particularly susceptible to certain medications, one of which is called retinoic acid (ATRA). Studies have shown that when ATRA is given with standard leukemia chemotherapy, there is a much greater chance of resulting in cure than in any of the other known AML's where ATRA has no effect.

The treatment of APL is aimed at first making the symptoms of the leukemia disappear, and next to cure the patient of the disease for good.  While there is a good chance to succeed in these goals, they can only be reached by applying a complicated and lengthy treatment that is divided into different phases.  The first phase is called induction therapy. During this phase, you start by taking the ATRA by mouth followed by infusion of 1 to 2 chemotherapy agents. The chemotherapy is given over approximately one week, and the ATRA is given for up to 3 months with the goal of this phase being to destroy all of the measurable leukemia cells in the blood and bone marrow. The treatment will result in a significant suppression of the blood count, and it usually takes approximately 30 days after starting chemotherapy before the blood counts normalize.  Alyssa will remain in the hospital during this time. Once the blood count has recovered and there is no evidence in the bone marrow, Alyssa will be in remission. However, even when there are no visible leukemia cells in the blood or marrow, without further treatment, residual leukemia cells present at a level that can't be seen will grow, causing a relapse. Thus further chemotherapy is needed to prevent these cells from multiplying  and causing a relapse. The chemotherapy after induction is called consolidation.  Repeated courses of consolidation will be needed and this will be followed by maintenance therapy with the entire treatment lasting approximately 18 months. After the initial hospital stay, the other courses of chemotherapy can be received as outpatient