Current treatment practices for childhood ALL

This study examined evidence on treatment practices for childhood acute lymphoblastic leukemia (ALL).

ALL is a type of cancer in which the bone marrow makes too many lymphoblasts (a type of immature white blood cell). It is the most common type of childhood cancer. Advances in risk classification, supportive care, and treatment have improved survival for ALL patients over the past few decades. 5-year survival rates of childhood ALL have been estimated to be over 85%. Further increases in cure rates can be expected with the discovery of additional recurrent genetic abnormalities, as well as continued efforts to optimize treatment strategies and the development of new targeted treatments and screening.

The aim of this study was to review evidence on treatment practices for childhood ALL.

ALL is typically classified into standard-, medium-, and high-risk. Using predictors of treatment success is important to help select treatment strategies for patients. For example, targeted therapy drugs called tyrosine kinase inhibitors, such as imatinib (Gleevec), can be added to standard chemotherapy for ALL patients with specific genetic changes (positive for the BCR-ABL) to improve outcomes. Minimal residual disease (MRD) refers to small number of leukemia cancer cells that remain after treatment. A number of studies reported MRD levels (on Day 46 or 78 of treatment) as the most important predictor of clinical outcomes in children with ALL.

Complete remission rates after induction therapy (standard chemotherapy to induce remission) range between 98 to 99%. However, recent evidence is suggesting that induction therapy is not as important as later therapies aimed to maintain remission in standard-risk patients. Patients with some MRD after induction therapy had similar 5-year survival rates (90.9%) to those who were negative for MRD (94.5%) if they received intensified therapy after achieving remission. MRD levels after 2 weeks of remission are an effective predictor to guide ongoing and future treatment approaches.

Two studies found that administering steroid drugs (such as dexamethasone and prednisone) at a high dose before and during induction therapy improved outcomes for children with ALL under the age of 10 years. High-dose dexamethasone is not recommended for children aged 10 years or older with B-cell ALL (the most common subtype) because of possible side effects.

Effective consolidation therapy (to maintain remission after induction therapy) is essential for all patients with ALL. This treatment regimen typically includes steroid drugs, chemotherapies (including vincristine and asparaginase), and central nervous system prophylaxis (to avoid cancer spread). This is followed by long-term maintenance therapy. Maintenance therapy usually consists of daily mercaptopurine (Purinethol) and weekly methotrexate (Otrexup) for about 2 years. Giving patients the maximum dosage of maintenance therapy they can tolerate has been found to improve long-term outcomes.

Two separate studies have shown that prophylactic (protective) radiation therapy to the head to prevent the cancer spreading to the brain for high-risk ALL is no longer needed in most patients. With modern chemotherapy regimens, survival rates and relapse rates are not worse for patients not receiving prophylactic radiation to the head.

This study reported on current treatment practices for childhood ALL.