Research Article v-3 andv-6 Polyunsaturated Fatty Acid Intakes and the Risk of Breast Cancer in Mexican Women: Impact of Obesity Status

Background:w-3 polyunsaturated fatty acids (PUFA) couldplay aprotective role on the risk of breast cancer; however, little is known about this relation amongMexicanwomen.We evaluated the association betweenw-3 and w-6 PUFA intake and breast cancer risk by obesity status in Mexican women. Methods:Apopulation-based case–control studywas conducted inMexico, including 1,000 incident breast cancer cases and 1,074 controls matched to cases by age, health care system, and region. Women provided information on health and diet by in-person interview. Body mass index (BMI) measures were used to define overall obesity. Obesity statuswas categorized as normal weight (18.5 < BMI < 25), overweight (25 BMI < 30), andobese (BMI 30).A conditional logistic regressionmodelwasused to assess the association betweenPUFA and breast cancer risk. Results: Overall, there was no significant association between w-3 PUFA intake and breast cancer risk (P 0.31).An increased riskof breast cancerwas associatedwith increasingw-6PUFA intake inpremenopausal women [OR 1.92, 95 % confidence interval (CI) 1.13–3.26; P 0.04]. A decreased risk of breast cancer was significantly associated with increasing w-3 PUFA intake in obese women (OR 0.58, 95 % CI 0.39–0.87; P 0.008) but not in normal weight nor in overweight women (Pheterogeneity 0.017). Conclusions:Obesity statusmay affect the association betweenw-3 PUFA intake and breast cancer risk. The underlyingmechanismsmaybe related todecreased inflammation and improved adipokin andestrogen levels induced by w-3 PUFA in adipose tissue in obese women. Impact: Increased intake of w-3 PUFA should be recommended among Mexican women in particular in obese women. Cancer Epidemiol Biomarkers Prev; 21(2); 319–26. 2011 AACR