Development and evaluation of the ENRICH (Exercise and Nutrition Routine Improving Cancer Health) healthy lifestyle program for cancer survivors and carers: A randomised controlled trial

National and international guidelines recommend physical activity, consuming a healthy diet, and maintaining a healthy weight can improve the health of cancer survivors. Despite these recommendations, there is limited evidence on how to best encourage cancer survivors and carers to adopt these healthy lifestyle behaviours. Using theory to design interventions using well-established and effective behaviour change strategies offers a promising way to improve lifestyle behaviours. This thesis by publication presents a series of studies that were conducted to address this gap in the literature. The aims are: i) to systematically review and synthesise the evidence regarding social cognitive theory-based nutrition and physical activity interventions for cancer survivors and describe the development of a theoretically-based intervention (ENRICH: Exercise and Nutrition Routine Improving Cancer Health); and ii) to evaluate the short- and long-term efficacy of the intervention and examine potential mediators of physical activity behaviour change. Social cognitive theory-based lifestyle interventions can improve the physical activity and nutrition behaviours of cancer survivors, and this theory was used to underpin the development of a healthy lifestyle program. ENRICH program participants demonstrated improvements to pedometer-assessed physical activity, vegetable consumption, and weight in the short-term (20 weeks), with weight and physical activity improvements maintained at 12 months. Behavioural goal was the only social cognitive theory-based construct that was a mediator of intervention effect on pedometer-assessed physical activity, suggesting that the intervention may have exerted important effects on other theoretical constructs that were not assessed. This program of work provides evidence for the efficacy of a theoretically-based, multiple health behaviour lifestyle intervention for cancer survivors and carers in the short and long-term. Given the success of the ENRICH program, the Cancer Council NSW has subsequently adopted this program as a service offered to cancer survivors across New South Wales.