[Comment] Precision medicine for children with cancer

The underlying concept of precision medicine is simple. DNA is sequenced from tumour biopsies, genetic (and potentially epigenetic) changes that promote the proliferation and survival of cancer cells are identified, and drugs are selected to target these mutations. For tumours in adults with common driver mutations, such as BCR-ABL in chronic myeloid leukaemia or HER2 overexpression in breast cancer, targeted treatments have led to impressive improvements in survival. As DNA sequencing became more affordable, the idea that the identification of individual mutations in tumours would also allow for the selection of drugs that would improve survival seemed logical.