Physical activity and survival after breast cancer diagnosis: meta-analysis of published studies
Published data have shown that physical activity (PA) has a positive role on the primary prevention of breast cancer risk. However, the role of PA on breast cancer outcome has been controversial with inconsistent data. The lack of a meta-analysis that addresses that issue prompted the current report. A comprehensive literature search identified eight studies, of which two studies were excluded. The remaining six studies (12,108 patients with breast cancer) were included in this meta-analysis. Pre-diagnosis PA reduced all causes mortality by 18% but had no effect on breast cancer deaths. Post-diagnosis PA reduced breast cancer deaths by 34% (HR = 0.66, 95% CI, 0.57–0.77, P < 0.00001), all causes mortality by 41% (HR = 0.59, 95% CI, 0.53–0.65, P < 0.00001), and disease recurrence by 24% (HR = 0.76, 95% CI, 0.66–0.87, P = 0.00001). Breast cancer mortality was reduced by pre-diagnosis PA in women with body mass index (BMI) < 25 kg/m2, while post-diagnosis PA reduced that risk among those with BMI ≥ 25 kg/m2. On the other hand, post-diagnosis PA reduced all causes mortality regardless of the BMI. The analysis showed that post-diagnosis PA reduced breast cancer deaths (HR = 0.50, 95% CI, 0.34–0.74, P = 0.0005), and all causes mortality (HR = 0.36, 95% CI, 0.12–1.03, P = 0.06) among patients with estrogen receptor (ER)-positive tumor, while women with ER-negative disease showed no gain. The current meta-analysis provides evidence for an inverse relationship between PA and mortality in patients with breast cancer and supports the notion that appropriate PA should be embraced by breast cancer survivors.
KeywordsBreast cancer Physical activity Exercise Prognosis Mortality
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