Low Dose Tamoxifen With or Without Omega-3 Fatty Acids for Breast Cancer Risk Reduction

PRIMARY OBJECTIVES: I. To investigate average change in serum adiponectin within the low dose tamoxifen (LDTAM) + high dose omega-3-acid ethyl esters (omega-3 fatty acids) arm. II. To study the beneficial effects of addition of high dose omega-3 fatty acids to LDTAM by comparing the relative difference in change in serum adiponectin in overweight and obese high-risk postmenopausal women randomized to 6 months of LDTAM or LDTAM + high dose omega-3 fatty acids. SECONDARY OBJECTIVES: I. To determine effect of LDTAM +/- high dose omega-3 fatty acids on insulin resistance, insulin sensitivity, and insulin secretory function (homeostatic model assessment for insulin resistance \[HOMA-IR\], homeostatic model assessment of insulin sensitivity \[HOMA%S\] homeostatic model assessment of beta cell function, \[HOMA%B\]), respectively. II. To determine effect of LDTAM +/- high dose omega-3 fatty acid on benign breast tissue estrogen response gene index (ERGI). EXPLANATORY OBJECTIVES: I. Effect of change in red blood cell (RBC) omega-3:omega-6 fatty acid ratio on within arm change in blood adiponectin. II. Effect of change in RBC omega-3:omega-6 fatty acid ratio on within arm change in tissue ERGI. III. Effect of baseline bioavailable estradiol on within arm change in blood adiponectin. IV. Effect of baseline and 6-month bioavailable estradiol on within arm change in tissue ERGI. V. Effect of 6-month tamoxifen active metabolites (endoxifen and 4-hydroxy \[4OH\] tamoxifen) on change in ERGI. VI. Effect of eicosapentaenoic acid/docosahexaenoic acid (EPA/DHA) dietary intake as measured by DHA Food Frequency Questionnaire on RBC omega 3:6 fatty acid ratio change. EXPLORATORY OBJECTIVES: I. Assess within arm effects of LDTAM +/- high dose omega-3 fatty acids on serum triglycerides. II. Assess within arm effects of LDTAM +/- high dose omega-3 fatty acids on adiponectin:leptin ratio. III. Assess within arm effects of LDTAM +/- high dose omega-3 fatty acids on anterior gradient protein 2 homolog (AGR2) messenger ribonucleic acid (mRNA). IV. Assess within effects of LDTAM +/- high dose omega-3 fatty acids on forkhead box A1 (FOXA1) protein (immunohistochemistry \[IHC\]). V. Assess within arm effects of LDTAM +/- high dose omega-3 fatty acids on AGR2 protein (IHC). VI. Assess effects of LDTAM +/- high dose omega-3 fatty acids on Ki-67 (IHC) in individuals with \> 500 cells in baseline ThinPrep and measurable baseline Ki-67. OUTLINE: Participants are randomized to 1 of 2 groups. GROUP 1: Participants receive tamoxifen by mouth (PO) once daily (QD) for 180 days in the absence of unacceptable toxicity. Participants may continue to receive tamoxifen PO QD for up to 60 additional days in the case of scheduling delays. Participants also undergo mammography at screening and undergo random periareolar fine needle aspiration (RPFNA) and collection of blood samples at screening and on study. GROUP 2: Participants receive tamoxifen PO QD and omega-3 fatty acids PO twice daily (BID) for 180 days in the absence of unacceptable toxicity. Participants may continue to receive tamoxifen PO QD and omega-3 fatty acids PO BID for up to 60 additional days in the case of scheduling delays. Participants also undergo mammography at screening and undergo RPFNA and collection of blood samples at screening and on study. After completion of study intervention, participants are followed up at 21-35 days.