Mediators of the effect of neighborhood poverty on physical functioning among breast cancer survivors: A longitudinal study

Purpose Female breast cancer survivors, a large and growing population, experience impaired physical functioning after treatment. Survivors living in impoverished neighborhoods may suffer even greater impairment, but the mechanisms linking neighborhood poverty and individual outcomes are poorly understood. This study sought to identify mediators of the effect of neighborhood poverty on physical functioning using longitudinal data from a Missouri cancer registry-based sample of 909 female breast cancer survivors. Methods Survivors were recruited 1 year after diagnosis (Y1) and completed two telephone interviews, at Y1 and 1 year later (Y2). The association between census-tractlevel poverty and physical functioning (RAND SF-36) was tested using a multilevel a priori path model with 19 hypothesized mediators, demographic and socioeconomic confounders, and covariates. Hypothesized mediators included clinical and treatment variables, psychosocial factors (depression, stress, social support), perceived neighborhood characteristics, behavioral risk factors (physical activity, smoking, body mass index, alcohol use), and comorbidity. Results In unadjusted analysis, women living in neighborhoods with higher poverty were more likely to report lower physical functioning at Y2 (b = -.19, p\.001). The final mediated model fit the data well (v2(8) = 12.25, p = 0.14; CFI = .996; RMSEA = .024). The effect of neighborhood poverty on physical functioning was fully mediated by physical activity and body mass index. Conclusions Breast cancer survivors living in neighborhoods with greater poverty reported lower physical functioning, but this effect was fully explained by physical activity and body mass index. Community-based lifestyle interventions sensitive to the unique challenges faced by cancer survivors and the challenges of living in a highpoverty neighborhood are needed to ameliorate neighborhood socioeconomic disparities in physical functioning.