Given the importance of diet and PA to childhood cancer survivors’ long-term health and well-being, it is essential to encourage these behaviors as early in development as possible. Adolescence is a particularly crucial time during which these behaviors may have a large impact, both in terms of physical development and the development of lifelong habits related to these health behaviors across the lifespan.
Therefore, given the crucial role of these behaviors during adolescence for those with cancer, the current review summarizes the beneficial effects of diet and PA in adolescent cancer patients both during and after treatment, evaluates the success of interventions that have been developed to address these behaviors, and provides recommendations for future strategies on how to improve these behaviors in this population. Specific attention is given to interventions aimed at adolescents both during active treatment and in the survivorship period.
Importance of diet and PA for adolescents with cancer
Adolescence is a period of rapid physical growth resulting from the simultaneous release of various growth, thyroid, and sex hormones.10 At the most rapid period of growth following childhood, adolescents grow at a rate nearly identical to that of a toddler, during which time bones become harder, muscle development increases, and heart and lungs increase in both size and capacity.11,12 To achieve optimal physical growth and development, adolescents require adequate nutrition as well as PA to support muscle development and bone health.13,14
When a child or adolescent is diagnosed with cancer, normal growth and development can be undermined as a result of both the cancer and treatment-related toxicity. Not only are adolescents with cancer or childhood cancer survivors in need of adequate nutrition and PA to support typical development, but they are in even greater need of support for their development in the context of their cancer diagnosis and treatment.15 Although many associate cancer with weight loss and cachexia, such symptoms are generally confined to later-stage or more advanced disease, and over a third of survivors who are normal weight prior to diagnosis are considered overweight by the end of treatment.16 Weight gain and adverse body composition change that favors the accumulation of adipose tissue at the expense of lean body mass is particularly pronounced with treatment for specific brain tumors, acute leukemias, and lymphoma.17,18 As a result, child and adolescent cancer survivors exhibit several known risk factors for metabolic syndrome, including enlarged waist circumferences and increased body mass index measures, and high triglycerides and low-density lipoprotein cholesterol compared with their healthy siblings.19 Finally, compared with peers with no history of cancer, adolescent and young adult cancer survivors report a significantly higher prevalence of obesity, cardiovascular disease, hypertension, asthma, and poor general physical health, highlighting the importance of lifestyle choices on long-term health and well-being in this population.20
Despite the increased need for adequate nutrition and PA, a large proportion of adolescents with a history of cancer do not meet recommended guidelines for these health behaviors. In terms of nutrition, 39%–94% of survivors of childhood cancer do not meet national recommendations for dietary intake.21 Common deficiencies include calcium, vitamin D, folate, and iron, many of which play an important role in cardiovascular health and bone development.22,23 Research also indicates that over half of childhood cancer survivors consume more than 110% of their estimated energy needs on a daily basis, creating a risk for undue weight gain.23 A review conducted by Stolley et al found that childhood cancer survivors of all ages reported largely unhealthy dietary habits, with specific concern for low fruit and vegetable intake, low calcium intake, and high fat intake.24 These data, taken together with endocrine and metabolic effects secondary to several cancer types and treatment regimens, can greatly increase risk for childhood obesity.23 Demark-Wahnefried and colleagues reported that younger childhood cancer survivors (ie, those <18 years old) were more likely to meet calcium guidelines and eat five or more daily servings of fruits and vegetables compared with childhood cancer survivors who were older (ie, >18 years old), thus calling for early interventions that are able to “catch” poor dietary habits before they become ingrained.25
Similar to dietary behaviors, a large proportion of childhood cancer survivors do not meet PA recommendations.24,26,27 The PA of child and adolescent cancer survivors is generally classified according to Center for Disease Control and Prevention recommendations of at least 60 minutes of moderate to vigorous activity per day at least 5 days per week.28 Almost all published data indicate that less than 50% of childhood cancer survivors meet these PA guidelines.24,27 Data also suggest that these survivors are less active than healthy comparison groups.24,27 In light of evidence suggesting that child and adolescent cancer survivors take in more than their estimated energy needs, this deficit in PA may compound survivors’ risk for obesity, metabolic syndrome, bone-density deficiencies, and cardiovascular problems.