Biomarker of long-chain n-3 fatty acid intake and breast cancer: Accumulative evidence from an updated meta-analysis of epidemiological studies

Abstract

Objective: We aimed to summarize the up-to-date epidemiology evidence on biomarkers of long-chain (LC) n-3 fatty acid (FA) intake in relation to breast cancer (BC).

Methods: Epidemiology studies determining FA levels in biospecimen (circulating blood or adipose tissue (AT)) were identified from PubMed, EMBASE, and Cochrane Library databases until March 2018. Multivariate-adjusted risk ratios (RRs) with 95% confidence intervals (CIs) were pooled using a random-effect model. Difference in biospecimen proportions of LC n-3 FA between BC cases and non-cases were analyzed as a standardized mean difference (SMD).

Results: Thirteen cohort and eleven case-control studies were eligible for the present meta-analysis. The estimated SMD was -0.14 (95% CI: -0.27, -0.11) for LC n-3 FA and -0.27 (95% CI: -0.42, -0.11) for LC n-3/n-6 FA ratio. When comparing the top tertiles with the bottom baseline levels, circulating LC n-3 FA was significantly associated with a lower risk of BC (RR: 0.84, 95% CI: 0.74, 0.96), but not AT (RR: 1.02, 95% CI: 0.70, 1.48). Significant inverse dose-response associations were observed for each 1% increment of circulating 20:5n-3 and 22:6n-3.

Conclusion: This meta-analysis highlights that circulating LC n-3 FA as a biomarker of intake may be an independent predictive factor for BC, especially 20:5n-3 and 22:6n-3.

KEYWORDS:

• Diet
• biomarker
• breast cancer
• fatty acid
• meta-analysis

Author contributions

The authors’ contributions were as follows: Bo Yang, Xiao-Juan Guo and Duo Li conceived the idea and designed the study strategy; Xiao-Li Ren, Zhi-Yi Wang and Feng Zhao summarized the data; Bo Yang and Xiao-Li Ren drafted the manuscript; Bo Yang and Zhi-Yi Wang contributed to the data analysis; Liang Wang, Xiao-Juan Guo and Duo Li provided critical revision for important intellectual content of the manuscript.

Conflict of interest

The authors disclose no conflicts of interests.

Additional information

Funding

This work is supported by the National Basic Research Program of China (973 Program: 2015CB553604), by National Natural Science Foundation of China (NSFC: 81273054), by the Ph. D. Programs Foundation of Wenzhou Medical University of Zhejiang Province, China (89217015), and by 2017 Chinese Nutrition Society (CNS) Nutrition Research Foundation–DSM Research Fund (2017-008). The funders have no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.