The goal of this study was to identify demographic, medical, and social cognitive correlates of physical activity in a sample of early-stage lung cancer survivors. Individuals with less education reported lower engagement in moderate/strenuous physical activity and leisurely walking. This is consistent with findings from several studies in other cancer survivor populations [10
], as well as prior research on general adult populations [22
]. There are multiple potential explanations for such associations, including lower physical functioning, poorer overall health, and lower awareness of the health benefits of physical activity among individuals with less education [50
]. Lung cancer survivors with lower levels of education may be especially in need of interventions to promote physical activity. Older lung cancer survivors may also gain particular benefit from physical activity interventions, as they reported less engagement in leisurely walking. This may in part be due to older individuals' greater likelihood of having comorbid medical conditions that impair mobility [51
]. Additionally, individuals having a greater number of surgical complications reported engaging in less leisurely walking. Future research is needed to examine explanations for this association, such as whether complications were experienced to a greater degree by high-risk patients [52
] whose impairments and comorbidities contributed to their lower engagement in physical activity. Similarly, survivors with poorer pre-operative pulmonary function reported less engagement in moderate/strenuous physical activity, as assessed up to six years after surgery. These individuals may have an impaired functional ability to engage in moderate/strenuous physical activities and may benefit from interventions that promote low intensity activities.
With regard to the social cognitive variables, there was little evidence for associations between the perceived environmental factors and either moderate/strenuous physical activity or leisurely walking. Previous research has found inconsistent evidence regarding such associations in general adult populations [24
]. Although there is limited relevant research in medical populations, there is some evidence linking perceived environmental factors with physical activity among individuals with chronic diseases such as multiple sclerosis [53
] and type 2 diabetes [54
]. Thus, further examination of potential associations between environmental factors and physical activity is warranted in future studies of physical activity correlates in cancer survivors. These studies may benefit from examination of a broader set of environmental factors and types of activity (e.g., separate walking categories for recreation, transport, and work [55
]) than in the current study.
As hypothesized, lower levels of moderate/strenuous physical activity were reported by individuals with less positive physical activity outcome expectations and greater physical activity self-efficacy. This latter finding is consistent with prior research indicating that perceived behavioral control (a construct from the theory of planned behavior that is conceptually similar to self-efficacy) is associated with cancer survivors' physical activity intentions and behaviors [16
]. These results suggest that future interventions designed to increase lung cancer survivors' engagement in moderate/strenuous physical activity should focus on increasing individuals' physical activity outcome expectations and physical activity self-efficacy, which may be achieved via discussion of prior positive experiences with physical activity, modeling of vicarious experiences, and the provision of positive encouragement [26
]. Together, the social cognitive constructs explained 38% of the variance in moderate/strenuous physical activity, which compares favorably with the 14% to 37% of variance explained in prior studies that have utilized the theory of planned behavior to examine physical activity correlates in other cancer survivor populations [16
Reported physical activity social support from friends was positively associated with leisurely walking. Self-efficacy did not mediate this association, but was itself positively associated with leisurely walking. The association between outcome expectations and leisurely walking approached significance. Overall, these results indicate that interventions to promote leisurely walking among lung cancer survivors should target self-efficacy and outcome expectations, as well as encouraging individuals to identify one or more friends who can motivate, or join in with, survivors' walking activities. Together, the social cognitive constructs explained 19% of the variance in leisurely walking. This lower explained variance in leisurely walking compared to moderate/strenuous physical activity may in part be due to the fact that the measures of the social cognitive constructs referred to physical activity in general, rather than the specific behavior of leisurely walking.
In separate analyses of data from the current study, we found that individuals reporting lower activity had poorer QOL in several domains (Coups et al., unpublished data). Combining this knowledge with the results presented in this paper, there is a clear need to develop and test theory-driven physical activity interventions for lung cancer survivors. Such interventions should take into account the fact that lung cancer survivors are commonly older adults, many of whom have comorbid medical conditions along with impairments in multiple QOL domains [56
]. Interventions that promote walking may be well tolerated by lung cancer survivors, as it is a safe and commonly practiced activity that older adults can engage in at varying intensities. However, future research is needed to examine lung cancer survivors' preferences with regard to physical activity interventions. The current study focused on lung cancer survivors who completed surgical treatment from one to six years previously. Recent research has documented beneficial effects of immediately pre- or post-operative exercise training or pulmonary rehabilitation on multiple outcomes in lung cancer patients, including cardiorespiratory fitness, functional ability, peak exercise capacity, pulmonary function, and dyspnea [57
]. Such interventions also have the potential to reduce surgical complications and aid recovery [62
Study Limitations and Strengths
The study findings should be considered in view of several limitations. The sample consisted primarily of well educated, non-Hispanic white individuals, who were surgically treated for early-stage NSCLC. Thus, the results may not extrapolate to lung cancer patient groups with other demographic and medical characteristics. For the majority of participants, surgery consisted of a lobectomy. Future research is needed to further examine whether the extent of surgical resection is associated with subsequent physical activity. The cross-sectional study design did not permit testing of the causal direction of associations between social cognitive constructs and physical activity. Similarly, the mediational relationships examined in this study should be further tested in future longitudinal descriptive and intervention research. Future research on physical activity among lung cancer survivors may also benefit from the combined use of self-report and objective assessments of physical activity, as well as examination of potential reasons for differences in correlates of varying physical activity outcomes such as moderate/strenuous activity and leisurely walking. Strengths of the current study include its focus on an understudied cancer survivor population, a good response rate, and examination of a comprehensive set of demographic, medical, and social cognitive correlates of both moderate/strenuous physical activity and leisurely walking.
This study provides novel, important information regarding the correlates of physical activity in survivors of early-stage NSCLC. The study results highlight several subgroups of lung cancer survivors who may be most in need of physical activity interventions. Further, by identifying multiple social cognitive correlates of physical activity, the current study provides valuable information regarding theory-guided constructs that should be targeted in future physical activity interventions for lung cancer survivors. Such interventions have the potential to enhance lung cancer survivors' QOL and physical functioning.