Strength, physical activity, and age predict fatigue in older breast cancer survivors.

PURPOSE/
OBJECTIVES: To determine whether clinical characteristics, physical fitness, or physical activity predict fatigue in older, long-term breast cancer survivors.
DESIGN: Cross sectional.
SETTING: National Cancer Institute-designated cancer center in Portland, OR. SAMPLE: 47 women (X age = 69 years) who were at least one year beyond treatment completion, including surgery, radiation, chemotherapy, or hormone therapy, for early-stage breast cancer.
METHODS: Participants completed one two-hour testing session to determine fatigue ratings, clinical information, submaximal aerobic fitness, lower-extremity muscle strength, body composition, and physical activity levels. MAIN RESEARCH VARIABLES: Self-reported fatigue assessed by the Schwartz Cancer Fatigue Scale, cancer and treatment history obtained by self-report, submaximal aerobic fitness assessed by 12-minute walk distance, lower-extremity muscle strength assessed by number of chair stands completed in 30 seconds, body composition assessed as percentage of body fat, and physical activity levels assessed by self-reported hours per week.
FINDINGS: Fatigue was significantly correlated with all independent variables, with the exception of aerobic fitness. Fatigue was higher with lower age, greater percentage of body fat, fewer years after diagnosis, more adjuvant treatments, poorer lower-extremity muscle strength, and less physical activity. In regression analyses, lower-extremity muscular strength, physical activity levels, and age each were significant independent predictors of fatigue. Lower-extremity muscle strength, physical activity, and age all were inversely related to fatigue and accounted for 15%, 7%, and 15% of the variance in fatigue scores, respectively.
CONCLUSIONS: In this sample of older breast cancer survivors, fatigue was linked to physical activity and muscle strength; women with better lower-extremity muscle strength, higher physical activity levels, and advanced age reported less fatigue. IMPLICATIONS FOR NURSING: A physical activity program aimed at improving lower body strength could mitigate persistent fatigue in older, long-term breast cancer survivors.