Friedenreich C M, Cust A E
Division of Population Health and Information, Alberta Cancer Board, 1331 29 St NW, Calgary, Alberta, Canada.
Br J Sports Med. 2008 Aug;42(8):636-47. doi: 10.1136/bjsm.2006.029132. Epub 2008 May 16.
To review (1) the epidemiological literature on physical activity and the risk of breast cancer, examining the effect of the different parameters of activity and effect modification within different population subgroups; and (2) the biological mechanisms whereby physical activity may influence the risk of breast cancer.
A review of all published literature to September 2007 was conducted using online databases; 34 case-control and 28 cohort studies were included. The impact of the different parameters of physical activity on the association between activity and the risk of breast cancer was examined by considering the type of activity performed, the timing of activity over the life course and the intensity of activity. Effect modification of this association by menopausal status, body mass index (BMI), racial group, family history of breast cancer, hormone receptor status, energy intake and parity were also considered.
Evidence for a risk reduction associated with increased physical activity was found in 47 (76%) of 62 studies included in this review with an average risk decrease of 25-30%. A dose-response effect existed in 28 of 33 studies. Stronger decreases in risk were observed for recreational activity, lifetime or later life activity, vigorous activity, among postmenopausal women, women with normal BMI, non-white racial groups, those with hormone receptor negative tumours, women without a family history of breast cancer and parous women.
The effect of physical activity on the risk of breast cancer is stronger in specific population subgroups and for certain parameters of activity that need to be further explored in future intervention trials.
（1）回顾关于身体活动与乳腺癌风险的流行病学文献，研究活动不同参数的影响以及不同人群亚组中的效应修正情况；（2）探讨身体活动可能影响乳腺癌风险的生物学机制。
利用在线数据库对截至2007年9月发表的所有文献进行综述；纳入了34项病例对照研究和28项队列研究。通过考虑所进行活动的类型、生命历程中活动的时间以及活动强度，研究身体活动不同参数对活动与乳腺癌风险之间关联的影响。还考虑了绝经状态、体重指数（BMI）、种族、乳腺癌家族史、激素受体状态、能量摄入和生育状况对这种关联的效应修正。
在本综述纳入的62项研究中的47项（76%）中发现了身体活动增加与风险降低相关的证据，平均风险降低25% - 30%。33项研究中的28项存在剂量反应效应。在绝经后女性、BMI正常的女性、非白人种族群体、激素受体阴性肿瘤患者、无乳腺癌家族史的女性以及经产妇中，休闲活动、一生或晚年活动、剧烈活动的风险降低更为明显。
身体活动对乳腺癌风险的影响在特定人群亚组以及某些活动参数方面更强，这些需要在未来的干预试验中进一步探索。
