[Soy food intake and breast cancer risk: a meta-analysis]

To explore the association of soy food intake with breast cancer risk.

The epidemiological studies on soy food intake and breast cancer risk published from 1991 to April 2011 were searched from MEDLINE, Pubmed, EMBASE, Sci and CNKI databases. Meta-analysis was used to estimate the combined OR and 95% CI.

Twenty eight studies were selected for the meta-analysis, including 23 case-control studies and 5 cohort studies. The overall analysis showed that soy food intake was inversely associated with the risk of breast cancer. The pooled OR was 0.86 (95% CI 0.78 - 0.94) for the combination of both study designs. However, the protective effect was only observed in case-control studies (the pooled OR = 0.86, 95% CI 0.77 - 0.95) but not in cohort studies. The protective effect of soy food intake on breast cancer risk was observed among studies conducted in Asian countries (OR = 0.76, 95% CI 0.67- 0.87), whereas no association was found in studies from Western countries (OR = 1.01, 95% CI 0.93-1.09). The further stratified analysis showed that the protective effect was only found in studies conducted in Asian countries (pooled OR = 0.76, 95% CI 0.65 - 0.89 for 14 case-control studies and OR = 0.81,95% CI 0.70 - 0.92 for 3 cohort studies, respectively). Additionally, the protective effect was only found among postmenopausal women but not among premenopausal women.

According to the meta-analysis of studies conducted in Asian countries, soy food intake is inversely associated with the risk of breast cancer among Asian women, especially based on the results of meta-analysis of case-control studies.