Association between Dietary Factors and Breast Cancer Risk among Chinese Females: Systematic Review and Meta-analysis

Background: Evidence for associations between dietary factors and breast cancer risk is inconclusive amongChinese females. To evaluate this question, we conducted a systematic review of relevant case-control and cohortstudies.
Methods: Studies were systematically searched among 5 English databases (PudMed, ScienceDirect,Wiley, Clinicaltrials.gov, and Cochrane) and 3 Chinese databases (CNKI, WanFang, and VIP) until November2012. Random effects models were used to estimate summary odds ratios (ORs) and the corresponding 95%confidence intervals (CIs).
Results: Thirty one case-control studies and two cohort studies involving 9,299 casesand 11,413 controls were included. Consumption of both soy and fruit was significantly associated with decreasedrisk of breast cancer, with summary ORs of 0.65 (95% CIs: 0.43–0.99; I2=88.9%, P<0.001; N=13) and 0.66(95% CIs: 0.47–0.91; I2=76.7%, P<0.001; N=7), respectively. Consumption of fat was significantly associatedwith increased risk of breast cancer (OR=1.36; 95% CIs: 1.13–1.63; I2=47.9%, P=0.088; N=6). There was nonsignificantassociation between consumption of vegetables and breast cancer risk (OR=0.72; 95% CIs: 0.51–1.02; I2= 74.4%, P<0.001; N=9). However, sensitivity analysis based on adjusted ORs showed decreased risk of breastcancer was also associated with consumption of vegetables (OR=0.49; 95% CIs: 0.30-0.67).
Conclusion: Bothsoy food and fruit are significantly associated with decreased risk of breast cancer among Chinese females, andvegetables also seems to be protective while dietary fatexerts a promoting influence.