At a Glance Minimal residual disease (MRD) after treatment for acute lymphoblastic leukemia (ALL) can help predict a patient’s risk of relapse

MRD alone is informative, but may not always be enough for an accurate prognosis; adding microdeletion testing can help

Microdeletions in genes responsible for tumor suppression or lymphoblast differentiation are a common feature of ALL and, in some genes, can lead to high-risk ALL

A new risk score that incorporates both current prognostic methods and microdeletion testing may improve treatment decisions

Acute lymphoblastic leukemia (ALL) is the most common cancer of childhood – and despite its five-year survival rate of over 85 percent (1), it also remains the most common cause of cancer-related death in children. What factors influence a child’s likelihood of survival after a diagnosis of ALL? Age, subtype, white blood cell count at diagnosis, and spread of disease (for instance, into the central nervous system fluid) can all have a significant impact – but genetic abnormalities are a key contributor. Alterations to the chromosomes can take many forms, including translocations, deletions and aneuploidies. All of these can occur in ALL – and when they do, it’s likely that they can affect a patient’s treatment response, relapse risk, and ultimate likelihood of survival.

Minimal residual disease (MRD) – the continued presence of residual cancer cells in the patient’s bone marrow after treatment – is a vital factor when it comes to predicting the potential relapse and overall disease prognosis of ALL patients. Even a single cancer cell can reproduce and seed a disease recurrence that may be much more difficult to treat than the initial presentation. Fortunately, sensitive molecular techniques can detect residual disease based on unique gene rearrangements in B- and T-cell lineages and on recurrent genetic abnormalities characteristic of leukemias. Using this information in conjunction with other patient data, we can reasonably approximate the risk that a given patient will relapse, allowing us to plan treatment in accordance with that risk.