Cancer and nutrition are inextricably linked, from the effect of nutrition on the aetiology of certain cancers, the impact of eating habits, quality of nutrition ingested and changes in nutritional status as a result of cancer and its presenting symptoms, to the consequences of cancer treatment pathways on nutrition intake and nutrients utilisation. Cancer can increase the need for artificial nutrition support and present ethical dilemmas about the provision of such interventions.Cancer is a disease with over 200 different types, each one having specific criteria for diagnosis, tumour identification and treatment with the potential to influence food intake, fluid and ultimately nutritional status and body composition. Increasingly, quality and quantity of nutritional intake alongside with lifestyle behaviours are linked to longer term health outcomes. 1 This special issue brings together substantial systematic reviews and narrative reviews focusing on nutrition from the point of diagnosis of cancer, through treatment and into living with and beyond cancer. These include key topics that will influence many people as half the adult population will experience cancer in their lifetime. 2 Nutrition is crucial around the time of diagnosis and in recent years, there has been increased focus on the value of 'prehabilitation'. This can be described as health optimisation prior to treatment through interventions such as diet, exercise, psychological and behaviour change support. 3 The focus is on improving fitness, nutritional status and psychological resilience with the aim of reducing treatment morbidity, length of hospital stay, improving health outcomes and quality of life. Key papers in this special issue add to the evidence base as researchers and clinicians continue to discuss the who, what, why and when of these complex interventions.