ASPO Abstracts
A dietary pattern based on estrogen metabolism is associated with postmenopausal breast cancer risk in a prospective cohort of women.
Category: Lifestyles Behavior, Energy Balance & Chemoprevention, Lifestyles Behavior, Energy Balance & Chemoprevention
Conference Year: 2018
Abstract Body:
Increased exposure to estrogen is an established risk factor for postmenopausal breast cancer, and dietary factors have been shown to influence estrogen metabolism. However, results of diet and breast cancer studies have been inconclusive. We developed a dietary pattern associated with serum levels of unconjugated estradiol (E2) and the ratio of 2- to 16-hydroxylated estrogen metabolites (2/16 ratio) in a subsample (n=653) of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial (PLCO) using reduced rank regression. We examined the association between the estrogen-related dietary pattern (ERDP) with prospectively collected postmenopausal breast cancer outcomes in the larger PLCO cohort (n=27,488) with Cox proportional hazards models. The ERDP, which positively correlated with E2 (r=0.27; p<0.0001) and inversely correlated with the 2/16 ratio (r=-0.16; p<0.0001), was comprised of positively weighted intakes for non-whole/refined grains, tomatoes, cruciferous vegetables, cheese, fish/shellfish high in ω-3 fatty acids, franks/luncheon meats and negatively weighted intakes for nuts and seeds, other vegetables, fish/shellfish low in ω-3 fatty acids, yogurt, and coffee. During 298,390 person-years there were 1,592 confirmed incident cases of breast cancer (n=1,248 invasive). A 1-unit increase in the ERDP score (range of -4.52 to 6.58) was associated with a 9%, 13%, and 13% increase in total (HR: 1.09, 95%CI: 1.01-1.18), invasive (HR: 1.13; 95%CI: 1.04=1.04-1.24) and estrogen receptor positive (ER+; HR: 1.13, 95%CI: 1.02- 1.24) breast cancer risk, respectively, after adjustment for confounders. Associations were seen for the fourth quartile of ERDP for overall breast cancer (HR: 1.14; 95% CI: 0.98, 1.32), invasive (HR: 1.20, 95%CI: 1.02, 1.42) and ER+ (HR: 1.19; 95%CI: 0.99-1.41) breast cancer compared to the first quartile. The increased risk associated with increasing ERDP scores was more apparent in strata of some effect modifiers (hormone replacement therapy and obesity) where participants’ relative estrogen exposure was lowest. Our results suggest that a dietary pattern associated with estrogen metabolites may influence postmenopausal breast cancer risk.
Keywords: dietary pattern, estrogen metabolism, breast cancer