[Comment] Finding the health-care expenditure that drives variation in cancer survival

EUROCARE1,2 and other international comparison studies of cancer survival3,4 provide essential evidence for reporting inequalities and monitoring population-level improvements. Research in this area continues to refute the long-standing criticisms5 of the comparability of international survival data. Cancer survival is a key metric that reflects improvements in treatment and care for patients diagnosed with cancer (ie, trends in survival can closely map to the timing of treatment advances). Researchers should always critically reflect on whether data are sufficiently comparable, interpret survival trends in the context of changes in incidence or mortality rates,6 and ensure analyses are stratified by key prognostic variables to isolate drivers of the differences.