The cardiotoxic effects of chemotherapy and radiation have been shown to contribute to an increased risk of cardiovascular disease in survivors of childhood cancer [1]. Consequently, childhood cancer survivors (CCS) are more than six times more likely to experience serious cardiac conditions compared with their siblings, with rates continuing to increase as late as thirty years after cancer treatment [2].

One of the key predisposing factors for cardiovascular disease is metabolic syndrome, a cluster of conditions which includes central obesity, dyslipidemia, glucose intolerance and hypertension [3]. There is a strong association between a diet low in fruit and vegetables and high in saturated fat and sugar, and the onset of metabolic syndrome in CCS [4]. Consequently, CCS with metabolic syndrome are twice less likely to meet national dietary guidelines compared with those who do not have the syndrome [4].

Despite their increased risk of developing serious chronic health conditions, young CCS often report poor health-protecting behaviors [5-8] (eg, reduced intake of fruit and vegetables, excessive energy, and inadequate calcium and folate intake) [9] and a higher intake of non-core (“junk”) foods compared with prediagnosis [10]. These behaviors often develop during treatment when children’s home food environment and eating are disrupted by frequent hospital admissions and treatment related side-effects including nausea, increased appetite, and vomiting [11]. Unhealthy eating habits established during cancer treatment also appear to be exacerbated by parents of CCS who report using unhealthy food as a means to reduce children’s pain and emotional distress after cancer treatment [10,11].

Although dietary behaviors are among the most easily modifiable factors for reducing the risk of cardio metabolic complications, CCS and their families often live long distances from their tertiary hospital [12] making it difficult for health professionals to provide ongoing nutritional support after treatment completion. Telephone interventions may therefore represent a feasible and acceptable approach for promoting healthy eating habits among CCS.

Telephone-based parent-led interventions have successfully increased fruit and vegetable intake in children not previously treated for cancer [13-17]. However, the feasibility and acceptability of telephone-based, parent-led fruit and vegetable interventions in CCS is yet to be evaluated. Therefore, we aim to assess the feasibility and acceptability of delivering evidence-based telephone nutritional support to parents of CCS.

Initial planning for Reboot Kids began in 2015 via a collaboration with the developers of the ‘Good for kids: Healthy Habits program’ at the University of Newcastle [15]. Healthy Habits is an evidence-based fruit and vegetable program delivered to nearly 400 Australian families. With their consent, our team updated the original parent guidebook to include the most recent version of the Australian Dietary Guidelines and Nutrition Australia Healthy Eating Pyramid, and dietitian approved recipes. To promote immediate and long-lasting intervention changes, we also followed recommendations by the original developers to focus on parent providing of fruit and vegetables to CCS, which mediated the short-and-long-term effectiveness of the intervention [22]. We therefore modified the initial behavior change technique from parenting self-monitoring of CCS daily fruit and vegetable intake to occasions of parent providing of fruit and vegetables to CCS over three days (Table 1).

Ethics approval was obtained on 11th November 2015 (HREC/15/SCHN/395) and recruitment commenced in August 2016. Of the 20 participants we aim to recruit, 7 have completed the intervention (including the booster session), 1 declined to participate after consenting, 2 participants dropped out after completing the first session, 8 are actively completing the intervention and 3 participants are providing consent. We aim to recruit the remaining participants via telephone follow-up calls and complete the intervention by July 2018.

This paper outlines the protocol for a pre-post, parent-led behavioral nutrition intervention for CCS, previously evaluated in a non-cancer pediatric population [15,16]. Although interventions piloted in non-cancer pediatric populations have led to significant increases in child fruit and vegetable intake [16], there is no research on their effectiveness in this high-risk population of CCS [34]; highlighting the unique contribution of the Reboot program [35].

We anticipate that the multimodal approach used in Reboot, encompassing a written parent guidebook and semi-structured telephone calls will contribute to the aim of the study. Telephone contact as the primary mode of intervention delivery can be efficacious [36], providing parents with support from a healthcare professional without requiring travel [12]. This flexibility is important in ensuring equitable access to families of CCS living in rural and regional areas [12]. Parents of CCS also report a preference for workbooks which provide relevant information about their children’s health after treatment [12].

The number of intervention contacts is also known to moderate intervention effectiveness, with behavior change often requiring multiple points of contact [37]. Booster sessions are often recommended to reinforce or re-establish messages or behavior changes suggested during interventions [38]. Subsequently, we chose to modify the original intervention to include 1 booster session. However, there is no research on the impact of booster sessions in dietary interventions in CCS. Moreover, the effectiveness [38] and optimum timing [39] of booster sessions in the wider behavior change literature is also unclear [40]. Most studies suggest that booster sessions should be instituted within three months after the intervention is complete to maximize efficacy [38,39], supporting our design of a booster session at 6 weeks post-intervention.

The Reboot study design has both strengths and limitations. As a pilot study, the small sample size will limit the ability to draw definitive conclusions regarding the efficacy of the intervention in increasing fruit and vegetable intake among CCS. The study will, however, be most useful in assessing the feasibility and acceptability of delivering a behavioral nutrition intervention in this population (Textbox 1). The inherent vulnerabilities of using parent-report as a proxy for child intake also warrants consideration [41]. A recent study indicated that repeated 24-hour recalls were a more valid measurement of dietary intake in CCS compared with FFQs, which underestimated energy intake [28]. However, due to the participant burden of multiple 24-hour recalls [42], we aimed to reduce potential bias in intake measurement by using a single 3-pass 24-hour recall and a validated, parent-administered online FFQ.

The increasing use, and success, of technology-based, parent-led interventions in improving children’s fruit and vegetable intake [43] suggests that online or smart-phone delivered interventions may offer a cost-effective alternative to telephone-based behavior change support [44-46]. Alternatively, online or mobile phone interventions delivered together with minimal telephone support or text messaging, may also help to maintain important human interaction [47] whilst still reducing intervention delivery costs. Given the absence of evidence-based dietary interventions in CCS [48], experimentation with different modes of delivery is an important next step in identifying the most efficacious method for promoting healthy eating habits in this vulnerable population [47].

Subsequently, a future goal of this pilot study is to utilize our feasibility and acceptability data to inform the development of a randomized control trial to evaluate the efficacy of delivering reboot online via web-based modules with brief telephone support (15 minutes) to reinforce key messages, on CCS dietary intake, compared with a wait-list control. If successful, data obtained from the RCT will be used to support the implementation of Reboot by community organizations across Australia, especially those in rural and remote areas, where CCS have poorer access to preventive health care [49].