Lipid Intake and Breast Cancer Risk: Is There a Link? A New Focus and Meta-Analysis.

None

• The authors found no association between total fat, saturated fatty-acids, mono and poly-unsaturated fatty acids and cholesterol intake and breast cancer incidence in the general population and in pre-menopausal women.

• Among lifestyle-related breast cancer risk factors, the role of diet in breast cancer remains uncertain.
• The authors highlight a weak association between high SFA consumption and breast cancer risk in post-menopausal women.
• The authors found no association between total fat, saturated fatty-acids, mono and poly-unsaturated fatty acids and cholesterol intake and breast cancer incidence in the general population and in pre-menopausal women.

Objectives

• To determine if there is an association between total lipid intake, saturated fatty acid (SFA), Poly- and Mono-Unsaturated Fatty Acid (PUFA and MUFA) and cholesterol intake and breast cancer risk.

Results

• Forty-four articles were included in the meta-analysis, consisting of 28 case-control studies and 16 cohort studies.
• In total, this meta-analysis involved 1,185,896 women, of whom 54,553 had breast cancer.
• There was no association between total fat, SFA, MUFA, PUFA and cholesterol intake and breast cancer in the general population and in pre-menopausal women.
• In postmenopausal women, high SFA consumption was associated with increased breast cancer risk in case-control studies [relative risk (RR): 1.12; confidence interval (CI) 95%: 1.03–1.21; p = 0.006 but not in cohort studies (RR: 1.01; CI 95%: 0.85–1.19; p = 0.93).

Limitations

• Studies included in the meta-analysis were carried out on populations from five continents with significant cultural and dietary diversity, and well as different types of oils used in the diet

Conclusion

• At this stage, the authors state it is not possible to establish nutritional recommendations regarding the consumption of lipids to decrease breast cancer risk.

• The results of this meta-analysis does not demonstrate a statistically significant link between high consumption of total lipids, PUFA, MUFA and cholesterol and the occurrence of breast cancer.
• However, the results suggest that there is an association between SFA intake and breast cancer risk in postmenopausal women, although this was only found in case-controlled studies and not cohort studies.
• While obesity is a known breast cancer risk factor after menopause, the link between the effect of diet and the effect of obesity on the breast may be through different mechanisms.
• The authors investigated if high lipid consumption acts on breast tissue by the same mechanisms as obesity, and found the association between SFA intake and breast cancer risk in postmenopausal women must be through other biological explanations.
• The authors found that while high SFA consumption may increase breast cancer risk among post-menopausal women, biological mechanisms linking SFA and breast cancerogenesis are still unknown.
• The meta-analysis found high blood cholesterol levels appear to increase the risk of breast cancer. However, the authors could not confirm that high dietary cholesterol intake is a risk factor for breast cancer. The authors postulated this may be in part due to the low proportion of cholesterol (about 30%) in the diet, while the rest comes from the degradation of lipids and carbohydrates by the liver.

• As lipids can have different actions in the same family, studies should rather focus on specific lipid consumption