The effect of regular exercise on quality of life among breast cancer survivors.

The authors evaluated the effect of regular exercise during the first 36 months after cancer diagnosis on quality of life (QOL) in a population-based cohort study of 1,829 Chinese women diagnosed with breast cancer. The women were identified between 2002 and 2004 and were invited to participate in the study about 6 months after cancer diagnosis. Exercise was assessed approximately 6, 18, and 36 months after diagnosis, and a metabolic equivalent task (MET) score in hours per week was derived. A cumulative, weighted exercise-MET score was created for regular exercise during the 36-month postdiagnosis period. QOL was evaluated at 6 and 36 months postdiagnosis. Multiple linear regression and mixed models were conducted to evaluate the association between regular exercise and QOL, with adjustment for clinical prognostic factors and other potential confounders. Both exercise-MET scores measured during the first 6 or 36 months postdiagnosis and the weighted exercise-MET score over the 36-month postdiagnosis period were positively associated with total QOL score and physical, psychological, and social well-being scores assessed at 36 months postdiagnosis (all P for trend < 0.05). Compared with nonregular exercisers, women with higher exercise-MET scores (> or =8.3 MET-hours/week) were more likely to have higher scores for total QOL and specific QOL domains (all P < 0.05). The exercise-QOL association remained stable over time after cancer diagnosis. This study suggests that regular exercise after breast cancer diagnosis improves QOL.