OBJECTIVETo estimate the association between overweight, obesity and the risk of breast cancer in Chinese female population.

METHODSLiteratures published in China and abroad about overweight, obesity and breast cancer risk among Chinese females were searched. We used "breast cancer", "overweight", "obesity", "weight", "body mass index" and "risk factors" as keywords, to retrieve papers in Chinese literature databases including CNKI, Wanfang and Weipu database. The same strategy was used to retrieve English papers in English literature database including Embase database, PubMed, Science Direct, Elsevier and Cochrane database, supplemented by literature tracing method. Time range was from the founding of each database to April 2012. A total of 124 research papers were collected. Using Stata11.2 software, meta-analysis was conducted, combined odds ratio (OR) and 95% confidence interval (CI) were calculated to estimate the associations between overweight, obesity and the risk of breast cancer in Chinese female population.

RESULTSEighteen studies were included in meta-analysis, among them 12 studies were in Chinese and 6 were in English, with a number of 7217 cases and 81 605 controls. Results showed a 7.7% increased risk of breast cancer among overweight or obesity women (OR = 1.08, 95%CI: 1.04 - 1.12). Compared with normal BMI women, the OR (95%CI) of overweight or obesity women were 1.07 (1.03 - 1.11) and 1.56 (1.29 - 1.84) before and after the adjustment of menopausal status.

CONCLUSIONOverweight, obesity may be important risk factors of breast cancer in Chinese female population. The intervention and control activities may reduce the risk of breast cancer at population level.