Staging is not clinically relevant in CAYA acute leukaemias other than for the presence of CNS disease and, in boys, testicular disease. However, appropriate prognostic assessment and risk stratification is a critical element in treatment planning and should be clearly documented in the patient’s medical record. This should be evidence-based to ensure patients at the highest risk of relapse receive appropriately intensified therapy while those with more favourable prognosis (the lowest risk of relapse) receive therapy of reduced intensity to reduce complications.

The most important current factors for prognostic assessment and risk stratification are cytogenetics and response to treatment using MRD. Newer molecular markers with prognostic and potentially therapeutic relevance in acute leukaemia will become clinically routine in the near future (Pui et al. 2018; Tasian & Hunger 2017).