Background: Total fat intake may be associated with increased risk of breast cancer, and fish oil has beensuggested as a protection factor to breast cancer. But the effect of vegetable oils is inconclusive. We aimed toinvestigate the association with high vegetable oils consumption and breast cancer risk, and evaluated theirdose–response relationship. Design: We systematically searched the MEDLINE, EMBASE, Cochrane databases,and CNKI updated to December 2014, and identified all observational studies providing quantitative estimatesbetween breast cancer risk and different vegetable oils consumption. Fixed or random effect models were usedto estimate summary odds ratios for the highest vs. lowest intake, and dose-response relationship was assessedby restricted cubic spline model and generalized least-squares trend (GLST) model.
Results: Five prospectivecohort studies and 11 retrospective case-control studies, involving 11,161 breast cancer events from more than150,000 females, met the inclusion criteria. Compared with the lowest vegetable oils consumption, higher intakedidn’t increased the risk of breast cancer with pooled OR of 0.88 (95% CIs:0.77-1.01), and the result from doseresponseanalyses didn’t show a significant positive or negative trend on the breast cancer risk for each 10gvegetable oil/day increment (OR=0.98, 95% CIs: 0.95-1.01). In the subgroup analyses, the oils might impact onfemales with different strata of BMI. Higher olive oil intake showed a protective effect against breast cancerwith OR of 0.74 (95% CIs: 0.60-0.92), which was not significant among the three cohort studies.
Conclusions:This meta-analyses suggested that higher intake of vegetable oils is not associated with the higher risk of breastcancer. Olive oil might be a protective factor for the cancer occurrence among case-control studies and fromthe whole. Recall bias and imbalance in study location and vegetable oils subtypes shouldn’t be ignored. Moreprospective cohort studies are required to confirm the interaction of the impact of vegetable oils on differentpopulation and various cancer characteristic, and further investigate the relationship between different subtypeoils and breast cancer.