Tumour response, correlates of survival and clinical benefit

 Nature Reviews Clinical Oncology

 We are all familiar with the metrics of tumour shrinkage and time to the development of disease progression as important end points in clinical trials. This tenet is based on findings of numerous studies over several decades that have demonstrated a link between agents that cause tumour shrinkage in a cancer population and its correlation with an overall survival improvement. The problem is that the inevitable variation in how these definitions and criteria have been applied over many decades in clinical trials has led to different conclusions about the efficacy of a treatment. Added to this complexity are the following issues: non-measurable lesions, differences obtained with the method of assessment of progression (imaging versus clinical examination), changes in non-target lesions versus target lesions, impact of lesions that coalesce or split on treatment, to name but a few. When considering the additional complexities posed by these factors, it is perhaps not surprising that tumour response is often a poor indicator of survival outcome. Yet, how can this be reconciled to allow the field of oncology to move forward............