Abstract
OBJECTIVE: To estimate the 5-year trajectory of physical activity among women with breast cancer, and to evaluate biopsychosocial variables (health status, physical symptoms, health-related quality of life (HRQL), depressive symptoms, and social support), measured soon after breast cancer diagnosis, as predictors of the 5-year trajectory. METHODS: Women diagnosed with Stage II or III regional breast cancer (n=227), surgically treated and awaiting the start of adjuvant therapy completed baseline assessments of medical, psychological, and behavioral functioning. Follow-up evaluations were conducted every 4 months during the first year and every 6 months during the subsequent 4 years (12 assessments total during the 5-year study). Mixed-effects modeling was utilized to estimate the baseline level of physical activity as well as rate of change over time. Measures of physical health status, HRQL, depressive symptoms, and social support were included as predictors of the physical activity trajectory. RESULTS: A curvilinear pattern of change in physical activity was evident over the 5-year follow-up (p=0.002). Physical activity increased gradually during the first 18 months, then declined steadily over the subsequent 42 months. Poor physical health, depressive symptoms, and lower emotional HRQL were associated with less physical activity. Higher family support was associated with a slower decline in physical activity in the latter 42 months of the study. CONCLUSIONS: Emotional HRQL following diagnosis with breast cancer appears to be important for sustaining physical activity in the first 1-2 years following diagnosis. Physical activity interventions among breast cancer survivors should address depressive symptoms early in the course of treatment.