‘Treatment pathway’ refers to the sequence of previous treatments received, based on patient selection criteria and response to previous therapies, often reflected in clinical guidelines. Assessment of the position in the treatment pathway drives the definition of the treatment population and choice of appropriate comparator. This pathway may have changed during the course of the trial if a new medicine has been approved or new clinical guidelines have been implemented locally. In some cases, the introduction of the medicine of interest will itself alter the treatment pathway. Alternatively there may not yet be an established treatment pathway or sequencing, and as a result there may be variations across countries or health centres within countries.