Physical activity and quality of life among breast cancer survivors: Pink SWAN.

Purpose: To describe physical activity (PA) trajectories across 10 years post-breast cancer diagnosis and examine their association with quality of life (QoL).

Methods: Participants from the longitudinal Study of Women's Health Across the Nation who developed incident breast cancer completed the Quality of Life in Adult Cancer Survivors scale (QLACS) which has 12 domains. Breast cancer survivors (BCS) with at least one post-diagnosis measure of the Kaiser Physical Activity Survey (PA) were included (n = 96). We estimated metabolic equivalents of task minutes per week (MET-min/week) for the two most frequent sport/exercise activities. Group-based trajectory modeling determined PA trajectories over 10 years post-diagnosis. Analysis of covariance assessed associations between PA trajectory group and the three QLACS domains with the worst scores (fatigue, pain, and recurrence-related distress), adjusted for PA and other relevant covariates.

Results: There were four post-diagnosis PA trajectories: consistently very low/no PA ("inactive," 11.5%); consistently some, but below aerobic PA guideline ("below guideline," 48.9%); generally met aerobic PA guideline with a slight decline ("met guideline," 22.2%); and exceeded aerobic PA guideline ("exceeded guideline," 18.8%). In adjusted models, the below guideline group reported more fatigue than the met or exceeded groups and more pain than the met guideline group, but there were no group differences in recurrence-related distress.

Conclusion: The majority of BCS did not meet the aerobic PA guideline over 10 years post diagnosis. BCS who met the aerobic PA guideline reported less fatigue and pain compared to those who did not meet the guideline in adjusted analyses, suggesting a negative association between PA and QoL.