Pathways between physical activity and quality of life in African-American breast cancer survivors

Several studies have indicated that the relationship between physical activity and quality of life is not directed but mediated through various pathways. The purpose of this study was to assess the role of cancer-related fatigue, disability, and functional status as potential mediators in African-American breast cancer survivors. African-American breast cancer survivors (N = 135, mean age = 63) aged 55 years and older participated in a web-based survey consisting of measures assessing physical activity, functional status, cancer-related fatigue, disability, quality of life, and sociodemographic and medical characteristics. Structural equation modeling was used to assess the structural relationships among the constructs. The initial structural model fit the data and revealed a significant relationship between physical activity and quality of life (beta = 0.34, P < 0.01). Subsequent structural models with proposed complementary and mediating paths of fatigue, function, and disability fit the data. The adjusted model indicated that physical activity was no longer associated with quality of life (beta = 0.11, P > 0.05) and mediated through pathways of functional status and fatigue (total beta = 0.16, P < 0.01). The final adjusted model accounted for 32 % of the variance in quality of life. Our data suggest that physical activity may be indirectly related to quality of life through pathways consisting of fatigue and functional status. Further longitudinal studies are needed to test the pathways through which varying levels of physical activity influence cancer-related and quality of life outcomes in minority cancer survivors.