Long-term outcomes of the FRESH START trial: exploring the role of self-efficacy in cancer survivors' maintenance of dietary practices and physical activity.

Progress in the early detection and treatment of cancer has resulted in rapid increases in the number of cancer survivors [1-2]. Currently, there are over 12 million cancer survivors in the United States, representing about 4% of the population [3]. The increase in cancer survivors is expected to continue due to the aging population and continued improvement in cancer screening and care [1]. Although the growth in cancer survivors is a positive trend, the negative health consequences of cancer and its treatment are a public health concern. Compared to people without a cancer history, cancer survivors have an increased risk for developing secondary malignancies and other medical conditions, such as heart disease, diabetes, osteoporosis, and functional limitations [4-8]. Factors contributing to survivors’ elevated risk for medical conditions may include genetic predisposition, effects of cancer treatment, and lifestyle factors [9]. Unhealthy lifestyle practices, including inadequate physical activity (PA) and fruit and vegetable (F&V) consumption and high fat intake, have been associated with increased risk of cardiovascular disease and other chronic health conditions [9-11]. Conversely, recent data suggest that a healthy diet may reduce cancer-related biomarkers and risk of cancer recurrence, although results have been mixed [12-17]. Unfortunately, many cancer survivors do not meet national guidelines regarding diet and PA [18-20]. Indeed, results of national surveys have revealed few differences in health behaviors between individuals diagnosed with cancer and healthy or noncancer control participants [18-20]. In an effort to improve cancer survivors’ health behaviors, over 60 diet and PA intervention trials have been conducted with this patient population [21-22]. Results of these trials suggest that PA interventions improve cardiorespiratory fitness, physical function, and quality of life, and dietary interventions result in lower body weight and increased nutrition-related biomarkers [22-27]. FRESH START was the first diet and PA trial for cancer survivors to deliver the intervention exclusively via mailed print materials [28]. The trial enrolled breast and prostate cancer survivors throughout North America. At 1-year follow-up [28], both the attention control group who received publicly available materials on diet and PA and the intervention group who received materials that were tailored to their demographic and psychological characteristics and progress toward achieving lifestyle goals showed improvement in specific health behaviors (i.e., increased PA and F&V consumption and reduced fat intake) as well as enhanced diet quality (a construct that reflects the overall dietary pattern and compares it with food patterns related to reduced risk of morbidity and mortality that involve high consumption of F&V, whole grains, low fat dairy products, and lean meats) [29-31]. The intervention group, however, showed significantly greater improvement than the control group in PA and dietary behaviors. At 2-year follow-up, the intervention group continued to report better overall diet quality and lower fat intake compared to the control group, but did not differ from controls with regard to F&V intake or PA [32]. The FRESH START intervention was informed by Social Cognitive Theory in which key determinants of health behaviors include self-efficacy (i.e., confidence that one can perform health behaviors in a variety of circumstances), knowledge of the benefits and risks of the behavior, outcome expectations, health goals, and plans for achieving these goals [33-34]. According to this theory, self-efficacy plays a critical role in health behavior initiation and maintenance by directly influencing health behavior and by affecting several other determinants [34]. People with high levels of self-efficacy are hypothesized to set realistic goals for themselves, maintain favorable outcome expectations, and persevere in the face of challenges [33-34]. The FRESH START intervention was designed to impact self-efficacy and related variables by detailing the benefits of practicing the goal behavior and incremental tasks toward the goal with an emphasis on overcoming perceived barriers and providing encouragement or praise for goal attainment [28]. At intervention completion (1 year post-baseline), change in self-efficacy was found to partially explain the effects of the FRESH START intervention on dietary outcomes [35]. Although long-term maintenance of PA and a healthy diet is critical for reducing cancer survivors’ risk of disease [9-11], psychosocial factors that influence health behavior maintenance (i.e., continuation of health behaviors at least 6-12 months post-intervention) are largely unknown, despite calls for their exploration in health promotion intervention trials [36-38]. Rothman and other theorists have noted that factors involved in initiation of health behaviors such as self-efficacy may not necessarily predict maintenance of these behaviors long-term [38-39]. Few research efforts have been made, however, to determine effects of diet and PA interventions on health behaviors over substantial time periods and psychosocial mediators of these effects. To address this gap in the literature, the present study prospectively examined the potential role of self-efficacy in long-term maintenance of dietary practices and PA. Specifically, change in self-efficacy from baseline to year 1 was examined as a potential mediator of the effects of the FRESH START intervention on breast and prostate cancer survivors’ dietary outcomes at year 2. Based on Social Cognitive Theory [33] and prior research [35, 40-42], we hypothesized that change in self-efficacy for F&V intake would partially mediate the intervention’s effect on daily servings of F&V and that change in self-efficacy for fat restriction would partially mediate the intervention’s effect on the percentage of kcal from fat. We also hypothesized that change in self-efficacy for F&V intake and fat restriction would partially mediate the intervention’s effect on diet quality. Gender and age also were examined as potential moderators of the relations between self-efficacy and dietary outcomes, as self-efficacy for eating a healthy diet has been correlated with these demographic factors [35, 43]. Change in self-efficacy for PA was not a hypothesized mediator of the intervention’s effect on total minutes of PA per week because group assignment did not predict change in self-efficacy for PA at 1-year follow-up [35]. Instead, we hypothesized that change in self-efficacy for PA from baseline to year 1 would predict PA at year 2 across study conditions. Finally, we explored whether change in barriers to F&V intake and fat restriction from baseline to year 1 predicted dietary outcomes at year 2. We also explored whether change in barriers to PA from baseline to year 1 predicted PA at year 2. Our prior analysis indicated that group assignment was not associated with changes in barriers to F&V intake, fat restriction, and PA at 1-year follow-up [35], and, thus, changes in barriers were not analyzed as potential mediators of the intervention’s effects on study outcomes.