Nuanced Research Needed on the Value of Exercise for Childhood Cancer Survivors

Chelsea Goodenough, PhD

Further research is still required to determine the optimal timing, frequency, and intensity of physical activity for childhood cancer survivors, according to findings from a comprehensive literature review that was published in Aging and Cancer.¹

Notably, the review concluded that regular physical activity is linked to a decreased risk of cardiovascular disease and all-cause mortality among childhood cancer survivors. Increased neurocognition is an added benefit of participating in exercise. However, because different cancer therapies are linked to varying amounts cardiovascular tissue damage and impacted regenerative potential, the extent to which exercise and health are linked may greatly differ between survivors.

“Our review shows that modifiable lifestyle choices, including PA [physical activity], are likely effective in improving physical fitness and reducing the risk for future organ dysfunction,” Chelsea Goodenough, PhD, Epidemiology and Cancer Control Department, St Jude Children’s Research Hospital, and colleagues, explained in the study.

“Most research has been focused on improving physical fitness to [cardiovascular disease] risk, due to its association with early mortality in childhood cancer survivors. However, because childhood cancer survivors are also at increased risk for early onset endocrine, musculoskeletal, and severe neurological disorders, and because PA and associated gains in physical fitness mitigates risk for these diseases in other populations, observational and interventional work is needed to determine if increasing PA and improving physical fitness decreases the risk of future chronic disease in childhood cancer survivors.”

Currently, the 5-year survival rate associated with childhood cancer is greater than 80%; recent advancements in pediatric oncology have emphasized the need for better survivorship care plans. Unfortunately, frailty is observed at a higher rate among childhood cancer survivors than among their non-survivor peers. The rate of frailty among young adults who have survived cancer is comparable with that of adults in the general population over the age of 70 (7.9% vs 9.9%, respectively). Frailty is linked to a 2.2% increased risk of chronic disease (95% CI, 1.2-4.2), and consequently, childhood cancer survivors, on average, face 7.27 chronic health conditions (95% CI, 7.26-8.18). Frailty is also linked to an increased mortality risk among survivors (HR, 2.6; 95% CI, 1.2-6.2).

Exercise and physical activity have been shown to improve physical fitness and physiologic reserve, making it a prevention and mitigation method for frailty. Physical fitness is defined as the ability to “carry out daily tasks without undue fatigue” and is considered a physiological adaptation.

In March 2020, researchers conducted a comprehensive literary review, which included studies published in PubMed, Web of Science, Cumulative Index to Nursing and Allied Health Literature, and Cochrane databases via Ovid.

Searched keywords included “survivor” and “childhood cancer,” or “survivor” and “neoplasms” and “child.” These terms were cross referenced with the following keywords: “physical activity” or “exercise” or “exercise therapy” or “exercise tolerance” or “physical exertion” or “physical fitness” and “chronic disease” or “organ dysfunction” or “late effect” or “mortality.” In addition to all papers flagged by the previously mentioned keywords, researchers also reviewed the reference sections listed with relevant papers.

Overall, 595 studies were assessed, and 11 study results were presented in the review. Researchers concluded that survivors who regularly exercised had both improved markers of cardiovascular health and a decreased risk of overt cardiovascular disease, as well as a decreased risk of all-cause mortality, in comparison with their peers who do not regularly exercise.

“For survivors of childhood cancer, low physiological reserve may limit healthy, physiological adaptation from repeated bouts of PA, thus, increasing the risk of age-related chronic diseases. However, this does not mean that childhood cancer survivors should not engage in exercise,” the authors summarized. “The current literature demonstrates that survivors who engage in PA, even if they have past exposure to cardiotoxic therapies, have reduced risk of adverse cardiac outcomes.”

The authors concluded that more studies are needed to determine the most effective interventions—such as intervention timing, behavioral strategies, delivery mechanisms, and exercise dose—to improve physical fitness in survivors to a point where it would have an impact on chronic disease risk.

Reference

Wogksch D, Goodenough CG, Finch ER, et al. Physical activity and fitness in childhood cancer survivors: a scoping review. Aging Cancer. 2021;2(4):112-128. doi:10.1002/aac2.12042