Associations of erythrocyte-3 fatty acids with biomarkers of-3 fatty acids and inflammation in breast tissue

There is increasing evidence that chronic inflammation is associated with increased breast cancer risk. Long-chain omega-3 polyunsaturated fatty acids (LC-3PUFA) may reduce circulating biomarkers of inflammation; however associations of blood LC-3PUFA with breast tissue LC-3PUFA and breast tissue biomarkers of inflammation are not well understood. We conducted a cross-sectional analysis of breast tissue and blood samples from n=85 women with no history of breast cancer, who underwent breast reduction surgery. Fatty acids of erythrocytes and undissected breast tissues were analyzed by gas chromatography; C-reactive protein (CRP), interleukin (IL)-6 and IL-8 in plasma and tissue were measured by ELISA. Multivariable-adjusted regression models were used to estimate associations between erythrocyte LC-3PUFA and breast tissue biomarkers. Women in the highest erythrocyte LC-3PUFA tertile had LC-3PUFA concentrations in the breast 73% (95% CI: 31-128%; p trend<0.0001) higher than women in the lowest tertile. Associations for each individual LC-3PUFA were similar in magnitude. No significant association was found for the shorter -3 PUFA, -linolenic acid. Although compatible with no association, women in the highest tertile of erythrocyte eicosapentaenoic acid had a nonsignificant 32% (95% CI: -23 to 62%) reduced breast tissue CRP. No correlation was observed between erythrocyte -3 PUFA and tissue IL-6 or IL-8 concentrations. Our findings provide evidence that erythrocyte -3 fatty acids are valid measures of breast tissue concentrations, and limited evidence that inverse associations from prospective epidemiologic studies of blood LC-3PUFA and breast cancer risk may be partly explained by reductions in breast tissue inflammation; however, these findings require replication. What's new? Chronic inflammation may lead to breast cancer, and omega-3 fatty acids are known to combat inflammation. Do circulating omega-3 fatty acids levels predict breast cancer risk? This study tested breast tissue from cancer-free women who underwent breast reduction surgery. They found that concentrations of omega-3 fatty acids in the blood correlated well with their levels in breast tissue; thus, taking measurements from the blood can stand in for directly assessing breast tissue. These findings may help explain previous results showing that circulating omega-3 fatty acids are inversely associated with breast cancer risk.