Prospectively examining physical activity in young adult survivors of childhood cancer and healthy controls.

With childhood cancer survival rates exceeding 80% [1], there is greater emphasis on survivor long-term health and wellbeing. Data from the Childhood Cancer Survivor Study (CCSS) indicate that the majority of young adult survivors of childhood cancer (YASCC) experience at least one significant health condition [2], including cardiovascular problems[2–4] and obesity [5], and are at risk for subsequent cancers in adulthood [6]. This increased risk for health problems highlights the importance of health-promoting behaviors. Regular physical activity, in particular, may mitigate the severity of late effects and enhance quality of life [7]. Increasing evidence, however, suggests that YASCCs do not adequately take responsibility for their health and that young adults in general engage in suboptimal levels of health-promoting behaviors. Similar to the typical age-related trajectory of physical activity [8], survivor physical activity declines in late childhood and young adulthood [9,10]. In general, YASCCs do not meet physical activity recommendations and exercise less than controls [11,12]. However, the current literature on YASCC physical activity is limited by studies with small sample sizes [e.g., 4,13,14], no control group [e.g., 15,16,17] or the lack of a non-sibling control group [e.g., 9]. For example, a study from the CCSS found that 52% of survivors did not meet CDC activity guidelines and were more likely to be inactive than sibling controls [9]. Although this finding provides foundational evidence for physical activity deficits in YASCCs, additional studies are needed that compare survivor physical activity against non-sibling, healthy controls since physical activity among siblings is positively correlated due to known family influences on exercise [18]. Studies using sibling controls may underestimate the impact of a history of childhood cancer on physical activity levels in young adulthood since the magnitude of difference between survivors and siblings may be reduced due to shared family factors that influence physical activity. The only study comparing YASCC physical activity to healthy controls found similar rates of physical activity among groups, but was limited by a small sample [14]. Research exploring predictors of YASCC physical activity has identified demographic, medical, and psychosocial factors in cross-sectional studies. Younger survivor age, higher socioeconomic status (SES), and male gender [9] are related to higher rates of physical activity. Cancer type and treatment-related variables (e.g., cranial radiation) also have been associated with YASCC physical activity [9]. Late effects, including fatigue and cancer-related pain, have been cited as significant barriers to physical activity [19]. Investigations also have found strong associations between psychological variables and YASCC physical activity. Cancer-related anxiety, negative affect [19], and depression [9] have been associated with inactivity. Social withdrawal and antidepressant use during adolescence also has been related to increased risk of survivor inactivity in adulthood [20]. Oeffinger [21] proposed that examining the health beliefs of YASCC may offer a clinically useful framework for understanding the health behaviors of this vulnerable population. The health belief model [22] conceptualizes engagement in health promoting behaviors as, in part, the result of beliefs related to perceived vulnerability to health problems, perceived benefits and costs associated with the health behavior, and self-efficacy and locus of control. Consistent with this model [22], more positive beliefs about ability to engage in physical activity and fewer perceived negatives associated with exercise have been positively related with YASCC physical activity [15]. Few studies have examined YASCC psychological functioning and beliefs as predictors of physical activity while accounting for demographic and medical variables. Such research is important in order to establish these factors as viable targets for exercise-promoting interventions as demographic and medical variables are not readily modifiable. Given the limitations of the existing studies on YASCC physical activity, specifically the lack of non-sibling comparisons and the absence of prospective studies, additional research is needed that addresses these shortcomings. The objectives of this study were to compare levels of physical activity in YASCC and healthy controls two months after (Time 2) a medical appointment (Time 1) and to identify the psychological and belief factors associated with physical activity in YASCC over this two-month period. The two-month period is relevant given evidence for this length of time in forming and maintaining health-promoting habits such as exercise [23]. Specific hypotheses were: 1) YASCC participants would have lower levels of physical activity than the comparison group at Time 2; 2) within the YASCC group, medical factors, cancer treatment intensity and survivor health problems, will have individual negative associations with physical activity at Time 2; and 3) increased psychological distress and less adaptive beliefs at Time 1 would predict lower rates of YASCC physical activity at Time 2 after adjusting for demographic and medical variables.