Systematic evaluation of diet and PA interventions
To better understand the strategies used to target improvements in diet and PA, a systematic search of PubMed, Medline®, and PsycINFO® was conducted for studies published prior to October 2013. The search consisted of the subject headings and text words: “childhood cancer” or “pediatric cancer” combined with each of the following: “health behaviors”, “lifestyle”, “diet”, “nutrition”, “PA”, “exercise”, and “intervention”. All search results were limited to English language. A secondary search was conducted by manually reviewing the reference sections of the identified manuscripts. After obtaining all relevant manuscripts, abstracts were screened to ensure applicability to the topic. Manuscripts were excluded if they did not 1) report on an intervention addressing diet and/or PA; 2) include adolescents, defined as children between the ages of 11 and 19 years, either receiving treatment for or survivors of cancer; and 3) include a sample size of at least ten childhood cancer survivors and/or patients on active treatment for childhood cancer.
Of the ten interventions targeting adolescent nutrition and PA, one addressed both diet and PA, two addressed diet only, and seven addressed PA only. Interventions were heterogeneous across sample sizes (range = 9–251), ages (range = 3–30 years of age), diagnoses (acute lymphoblastic leukemia, brain tumor, mixed diagnoses), and targeted points of intervention (on-treatment, immediate post-completion of treatment, long-term survivorship). Specific details on the studies are presented in Table 1. The interventions and associated outcomes within the specified behaviors are addressed following.
Dietary behavioral interventions aimed at adolescents are limited. Of the two identified interventions, one dietary intervention aimed to improve bone health in a sample of 75 adolescent and young adult survivors who were one or more years off-treatment. Through a half-day behavioral workshop, the intervention aimed to increase participants’ awareness of cancer late-effects; reduce barriers to, and increase perceived benefits of, health-promoting behaviors; and improve self-efficacy to lead a healthy lifestyle with a specific emphasis on promotion of good bone-health habits.29 At 1-month follow-up, average milk consumption frequency (intervention = 3.36, standard deviation [SD] =0.72 versus control = 2.93, SD = 0.88) and past-month calcium supplementation (percent with any calcium supplementation 1-month post-intervention: 82.9% Intervention group versus 24.1% control group) were significantly greater in the intervention group compared with in the control group. At 1-month follow-up, the intervention group reported a 53.9% increase in participants with any calcium supplementation across the previous month compared with baseline, while the control group showed an increase of 2.5%. Neither long-term maintenance of bone-health behavior change nor impact on bone density was evaluated.
The second study to include diet as an outcome consisted of a randomized, controlled psychoeducational intervention that encouraged adolescent survivors to select one target health behavior known to be associated with cancer risk for improvement. No significant changes in survivor-selected health behavior changes related to diet were found following the year-long intervention and, interestingly, survivors in the intervention group showed a nonsignificant downward trend related to improved nutrition compared with survivors receiving standard of care (change score: intervention group = −0.10 versus standard of care group =0.01).30,31 However, the findings of this study are complicated by non-validated means of assessing dietary intake and expressed concerns that the intervention was delivered in a clinical setting that may have been distracting, if not anxiety provoking.
Comparatively more attention has been given to interventions targeting PA in adolescents with a history of cancer. Of the eight interventions targeting PA, five included survivors only, two included on-treatment participants only, and one included all adolescents diagnosed with cancer regardless of treatment status. Encouragingly, no studies reported negative outcomes for participants in terms of adverse events or perceived risk, either during treatment or during survivorship, suggesting that, from a medical standpoint, PA interventions are safe and appropriate for this population.
For those studies targeting PA in adolescent survivors, four of the six interventions showed significant change in outcomes related to PA following completion of the intervention.32–35 Of the studies reporting significant improvements, the majority included both psychoeducational and behavioral training components and involved trained interventionists to ensure participant adherence with the intervention. With the exception of the 4-day, adventure-based, PA-promoting intervention of Li et al,34 successful interventions occurred across multiple weeks (range = 6–16 weeks) and included a mix of both supervised and unsupervised PA sessions allowing participants to practice learned PA skills at home. Unfortunately, measured outcomes across interventions were variable, with some interventions relying on caregiver- or survivor-reported outcomes and others focusing on objective physiological data. Of the three interventions reporting objective physiological outcomes, results were equivocal for fitness tests including functional mobility, strength, and endurance.32,33,35 Of note, one study assessed markers of metabolic syndrome, a known risk in survivors of childhood cancer.33 In this 16-week home-based exercise program, results indicated that, immediately following the intervention, fasting plasma insulin (P = 0.01), insulin resistance (P = 0.002), waist circumference (P = 0.003), waist-to-hip ratio (P = 0.002), fat percent (P = 0.04), and supine diastolic blood pressure decreased (P = 0.03). These outcomes were supported by concurrent changes in fitness testing including peak oxygen uptake and maximal workload, which both increased by 5% (P = 0.01 and P = 0.002, respectively), and muscle strength (sit-up test [P = 0.01], back extensor test [P = 0.002], full squatting test [P = 0.0004]). Long-term maintenance of PA and related outcomes were not assessed.
Interventions conducted with adolescents receiving treatment for cancer showed more consistent results, with all three studies reporting significant change on one or more outcomes following the intervention. Keats and Culos-Reed35 conducted a 16-week group PA and educational intervention that resulted in increased self-reported PA, improved quality of life, and improved fatigue following completion of the study.35 Long-term maintenance of PA and fatigue gains were not sustained, though quality of life remained higher at the 12-month follow-up. Adherence across the 16-week intervention was 81.5%, further supporting the feasibility of PA interventions for adolescents receiving active cancer treatment.
The remaining intervention conducted with adolescents receiving active treatment was a physical therapy intervention implemented at diagnosis for patients with acute lymphoblastic leukemia (ALL).36 This intervention consisted of inpatient physical therapy evaluations and sessions during hospital admissions at multiple time points throughout treatment coupled with recommended exercises to be completed by the patient at home. Adherence was variable, which is not surprising given the lengthy time of treatment and significant complications that can occur during treatment for ALL. Participants were evaluated at diagnosis, 32 weeks post-diagnosis, 1 year post-diagnosis, at the cessation of treatment (approximately 2 years post-diagnosis), and 1 year posttreatment. Results indicated that body fat increased equally for all patients during treatment; however, participants who completed the intervention showed a more rapid decline of excess body fat following treatment compared with those receiving standard care (P = 0.013). One year following completion of treatment, the percentage of body fat had decreased in the intervention group (change in percent body fat of -1.08 SD scores) to a greater degree than in the control group (change in percent body fat of -0.49 SD scores [P = 0.013]). This is significant given the potential for excess weight gain during treatment for ALL followed by steady increases in weight through survivorship for some patients. While preliminary, this study suggests that interventions delivered during active therapy may help adolescents maintain or improve PA behaviors during treatment, thus preventing or blunting some of the more common physical deficits known to be associated with these diagnoses.