The Impact of the 6:3 Polyunsaturated Fatty Acid Ratio on Intermediate Markers of Breast Cancer

Evidence suggests omega-6 (n-6) polyunsaturated fatty acids (PUFAs) promote breast cancer whereas omega-3 (n-3) PUFAs inhibit breast cancer growth. These fatty acids may influence breast cancer development by impacting prostaglandin E2 (PGE2) formation and consequently estradiol synthesis. We sought to establish the relationship between erythrocyte n-6 and n-3 PUFAs with serum estradiol and breast density, two hormonally-related breast cancer risk factors. We hypothesized the n-6 PUFA's and the 6:3 PUFA ratio are positively related and n-3 PUFAs negatively related to both risk factors. Nonsteroidal anti-inflammatory drugs (NSAIDs) also inhibit PGE2 formation, therefore were further hypothesized that estradiollevels would be lower among NSAID users. Participants (n=260) were eligible for these analyses if they were cancer-free, postmenopausal and not taking exogenous hormones. Estradiol levels were significantly lower among current users of NSAIDs as compared to non-users of NSAIDs. Further, estradiol concentration decreased with increasing total n-3 PUFAs and rose with increasing total n-6 PUFAs and the 6:3 PUFA ratio; however, this was noted only among non-users of NSAIDs. No relationship was observed between any fatty acid measure and breast density. In summary, lowering n-6 intake, increasing n-3 intake, or taking a NSAID may result in reduced estradiol synthesis and potentially breast cancer risk.