An updated systematic review and meta-analysis on association of serum lipid profile with risk of breast cancer incidence

Background: This meta-analysis was performed to investigate the effect of serum lipids on the risk of breast cancer incidence. Methods: PubMed, Web of Science, Scopus, and EMBASE were searched systematically from January 1998 to April 2019. Inclusion criteria were English observational studies (cohort or case-control) and the concentration of at least one of the lipid profile components (total cholesterol/triglycerides/low-density lipoprotein cholesterol/high-density lipoprotein cholesterol) measured before a diagnosis of breast cancer (BC). The studies were included in which the relative risk (RR) had been reported with 95% confidence intervals (CIs). A random-effects model was used. Results: A total of 25 studies were found, including 2,882,789 participants in cohort studies with 45,481 cases with BC, and 1983 BC cases and 2963 case-control studies. Combined RR of cohort studies for the highest versus lowest for the BC was LDL-C: 0.95 (95% CI: 0.89-1.01), triglycerides (TG): 0.95 (95% CI: 0.91-0.99; P = 0.02), total cholesterol (TC): 0.98 (95% CI: 0.91-1.05), and HDL-C: 0.86 (95% CI: 0.63-1.18). Combined RR of case-control studies for the highest versus lowest was LDL-C: 1.08 (95% CI: 0.78-1.48), TG: 1.73 (95% CI: 0.94-3.18), TC: 1.02 (95% CI: 0.80-1.29), and HDL-C: 0.79 (95% CI: 0.65-0.97). Conclusions: Based on the results, it can be concluded that only TG but not TC and/or LDL-C had a significant inverse association with the risk of BC incidence. HDL-C showed a significant protective effect against breast cancer in postmenopausal women and case-control studies.