Red Meat Consumption and Breast Cancer Risk in Premenopausal Women: A Systematic Review and Meta-Analysis

Background: this comprehensive meta-analysis aimed to determine the impact of red meat consumption on breast cancer risk in premenopausal women. methods: we conducted a systematic search in major electronic databases (medline, scopus, and sciencedirect) until january 1^st, 2016 for all the casecontrol and cohort studies that addressed the association between red meat consumption and breast cancer risk. the full-texts of the retrieved articles were reviewed by two independent authors. the quality of the studies was assessed using a score assigned to each item according to strobe statement. we used the random effects model to obtain summary measures of odds ratio or relative risk with 95% confidence interval. results: out of the 513 retrieved studies, 17 (9 case-control and 8 cohort) were entered into the meta-analysis. these studies analyzed 26675 cases of breast cancer and over 943557 control or comparison subjects. the results of the random effects metaanalysis indicated a significant association between red meat consumption and breast cancer risk (relative risk: 1.269; 95% confidence interval: 1.117, 1.441; p-value for heterogeneity=0.002). the pooled relative risk was 1.087 (95% confidence interval: 0.999, 1.183) for cohort studies and 1.548 (95% confidence interval: 1.255, 1.909) for case-control studies. conclusion: the results of this meta-analysis showed that the women who consumed red meat had an increased risk of breast cancer. further studies are required to investigate this association.