Intrinsic capacity and resilience: Taking frailty to the next level.

In addition to frailty, two novel concepts have been introduced in the field of geriatrics to capture the heterogeneous ageing process: the first is intrinsic capacity, which uses a community-based, holistic approach and is propagated by the World Health Organization (WHO); and the second is resilience, which provides a more dynamic perspective on the individual's reserves, injury and recovery. While both concepts are linked to frailty, with all three focusing on reserves in relation to ageing, each approaches this issue from a different point of view. In this paper, we will compare and contrast these three concepts - frailty, intrinsic capacity and resilience - and assess their relevance to future geriatric oncology research as well as daily clinical practice.