Factors for the Primary Prevention of Breast Cancer: A Meta-Analysis of Prospective Cohort Studies

Background: this report provided the effect of 15 preventable factors on the risk of breast cancerincidence.study design: a systematic review and meta analysis.methods: a detailed research was conducted on pubmed, web of science, and scopusdatabases in january 2020. reference lists were also screened. prospective cohort studiesaddressing the associations between breast cancer and 15 factors were analyzed. between-studyheterogeneity was investigated using the χ2, τ2, and i2 statistics. the probability of publication biaswas explored using the begg and egger tests and trim-and-fill analysis. effect sizes were expressed as risk ratios (rrs) with 95% confidence intervals (cis) using a random-effects model.results: based on the results, out of 147,083 identified studies, 197 were eligible, including19,413,702 participants. the rrs (95% ci) of factors associated with breast cancer were asfollows: cigarette smoking 1.07 (1.05, 1.09); alcohol drinking 1.10 (1.07, 1.12); sufficient physicalactivity 0.90 (0.86, 0.95); overweight/obesity in premenopausal 0.92 (0.82, 1.03) andpostmenopausal 1.18 (1.13, 1.24); nulliparity 1.16 (1.03, 1.31); late pregnancy 1.37 (1.25, 1.50);breastfeeding 0.87 (0.81, 0.93); ever using oral contraceptive 1.00 (0.96, 1.05); ever using estrogen1.13 (1.04, 1.23); ever using progesterone 1.02 (0.84, 1.24); ever using estrogen/progesterone 1.60(1.42, 1.80); ever taking hormone replacement therapy 1.26 (1.20, 1.32); red meat consumption1.05 (1.00, 1.11); fruit/vegetable consumption 0.87 (0.83, 0.90); and history of radiation therapy,based on single study 1.31 (0.87, 1.98).conclusions: this meta-analysis provided a clear picture of several factors associated with thedevelopment of breast cancer. moreover, the useful information in this study may be utilized forranking and prioritizing preventable risk factors to implement effective prevention programs.