Lahart Ian Matthew, Metsios George S, Nevill Alan Michael, Carmichael Amtul Razzaq
Faculty of Education, Health and Wellbeing, University of Wolverhampton, Walsall Campus , Gorway Road, Walsall , UK.
Acta Oncol. 2015 May;54(5):635-54. doi: 10.3109/0284186X.2014.998275. Epub 2015 Mar 9.
Strong evidence exists supporting the effect of lack of physical activity on the risk of developing breast cancer. However, studies examining the effects of physical activity on breast cancer outcomes, including survival and prognosis have been inconclusive. Therefore, the aim of the current study was to provide a systematic review and meta-analysis of studies investigating the association between physical activity and breast cancer recurrence and death.
PubMed, EMBASE, and CENTRAL databases were searched up to 18 October 2014. Reference lists of retrieved articles and relevant previous reviews were also searched. Observational studies that reported risk estimates for all-cause and/or breast cancer-related death and/or breast cancer recurrences by levels of physical activity, were included in the review. Random effects models were used to calculate pooled hazard ratios (HR) and 95% confidence intervals (CI) and to incorporate variation between studies. The Newcastle-Ottawa scale was used to critically appraise the risk of bias across studies.
Twenty-two prospective cohort studies were eligible in this meta-analysis. During average follow-up periods ranging from 4.3 to 12.7 years there were 123 574 participants, 6898 all-cause deaths and 5462 breast cancer outcomes (i.e. breast cancer-related deaths or recurrences). The average Newcastle-Ottawa score was six stars (range 4-8). Compared to those who reported low/no lifetime recreational pre-diagnosis physical activity, participants who reported high lifetime recreational pre-diagnosis physical activity levels had a significantly lower risk of all-cause (HR = 0.82, 95% CI 0.70-0.96, p < 0.05) and breast cancer-related death (HR = 0.73, 95% CI 0.54-0.98, p < 0.05). Significant risk reductions for all-cause and breast cancer-related death was also demonstrated for more recent pre-diagnosis recreational physical activity (HR = 0.73, 95% CI 0.65-0.82, p < 0.001; and HR = 0.84, 95% CI 0.73-0.97, p < 0.05, respectively), post-diagnosis physical activity (HR = 0.52, 95% CI 0.43-0.64, p < 0.01; and HR = 0.59, 95% CI 0.45-0.78, p < 0.05, respectively) and meeting recommended physical activity guidelines (i.e. ≥ 8 MET-h/wk) post-diagnosis (HR = 0.54, 95% CI 0.38-0.76, p < 0.01; and HR = 0.67, 95% CI 0.50-0.90, p < 0.01, respectively). However, there was evidence of heterogeneity across lifetime recreational pre- and post-diagnosis physical activity analyses. Both pre-diagnosis (lifetime and more recent combined) and post-diagnosis physical activity were also associated with reduced risk of breast cancer events (breast cancer progression, new primaries and recurrence combined) (HR = 0.72 95% CI 0.56-0.91, p < 0.01; and HR = 0.79, 95% CI 0.63-0.98, p < 0.05, respectively).
There is an inverse relationship between physical activity and all-cause, breast cancer-related death and breast cancer events. The current meta-analysis supports the notion that appropriate physical activity may be an important intervention for reducing death and breast cancer events among breast cancer survivors.
有强有力的证据支持缺乏体育活动会增加患乳腺癌风险这一观点。然而，关于体育活动对乳腺癌预后（包括生存率和预后）影响的研究尚无定论。因此，本研究的目的是对调查体育活动与乳腺癌复发及死亡之间关联的研究进行系统综述和荟萃分析。
检索截至2014年10月18日的PubMed、EMBASE和CENTRAL数据库。还检索了检索文章的参考文献列表以及之前相关的综述。纳入本综述的观察性研究需报告按体育活动水平划分的全因死亡和/或乳腺癌相关死亡及/或乳腺癌复发的风险估计值。采用随机效应模型计算合并风险比（HR）和95%置信区间（CI），并纳入研究间的差异。使用纽卡斯尔-渥太华量表对各研究的偏倚风险进行严格评估。
本荟萃分析纳入了22项前瞻性队列研究。在平均4.3至12.7年的随访期内，共有123574名参与者，6898例全因死亡和5462例乳腺癌结局（即乳腺癌相关死亡或复发）。纽卡斯尔-渥太华量表平均得分为六星（范围4 - 8）。与报告终生休闲性诊断前体育活动水平低/无的参与者相比，报告终生休闲性诊断前体育活动水平高的参与者全因死亡风险显著降低（HR = 0.82，95% CI 0.70 - 0.96，p < 0.05），乳腺癌相关死亡风险也显著降低（HR = 0.73，95% CI 0.54 - 0.98，p < 0.05）。近期诊断前休闲性体育活动（HR = 0.73，95% CI 0.65 - 0.82，p < 0.001；和HR = 0.84，95% CI 0.73 - 0.97，p < 0.05）、诊断后体育活动（HR = 0.52，95% CI 0.43 - 0.64，p < 0.01；和HR = 0.59，95% CI 0.45 - 0.78，p < 0.05）以及诊断后达到推荐体育活动指南（即≥8 MET - h/周）的参与者，全因死亡和乳腺癌相关死亡风险也显著降低（HR = 0.54，95% CI 0.38 - 0.76，p < 0.01；和HR = 0.67，95% CI 0.50 - 0.90，p < 0.01）。然而，终生休闲性诊断前和诊断后体育活动分析存在异质性证据。诊断前（终生和近期合并）和诊断后体育活动也与降低乳腺癌事件（乳腺癌进展、新发原发性肿瘤和复发合并）风险相关（HR = 0.72，95% CI 0.56 - 0.91，p < 0.01；和HR = 0.79，95% CI 0.63 - 0.98，p < 0.05）。
体育活动与全因死亡、乳腺癌相关死亡及乳腺癌事件之间存在负相关关系。当前的荟萃分析支持这样一种观点，即适当的体育活动可能是降低乳腺癌幸存者死亡和乳腺癌事件的重要干预措施。
