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 1st, 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.