Abstract P2-01-04: High-density lipoprotein cholesterol is associated with mammographic density in premenopausal women

Background : High-Density Lipoprotein Cholesterol (HDL-C), and ovarian steroid hormones and mammographic density have independently been associated with breast cancer development. However, little is known regarding the association between HDL-C, ovarian hormones and mammographic density in premenopausal women. Material and Methods : We assessed fasting HDL-C among 202 healthy women, aged 25-35 years, participating in the Energy Balance and Breast cancer Aspects (EBBA) study-I. Progesterone and estrogen were assessed both in serum (three times) and daily saliva across an entire menstrual cycle. Computer-assisted mammographic density (Madena) was obtained from digitized mammograms taken at days 7-12 of the menstrual cycle during a narrow time frame, thereby avoiding potential bias due to variations in mammographic density during the menstrual cycle. The association between HDL-C, in combination with progesterone or estrogen and absolute mammographic density were studied in multivariable linear and logistic regression models, and potential confounding factors and effect modifiers were tested. Results : The participating women had a mean age of 30.7, mean HDL-C of 1.54 mmol/l, and absolute breast density of 34.7 cm 2 (median 32.4 cm 2 ). Among women in the lowest tertile of HDL-C (≤1.38mmol/l), we observed a positive association between midmenstrual salivary 17β-estradiol and absolute breast density ( p = 0.014), and between luteal salivary progesterone and absolute breast density ( p = 0.029). Among these women in the lowest tertile of HDL-C, we also observed that high 17β-estradiol throughout the menstrual cycle was associated with higher absolute mammographic density (above median absolute density, >32.4 cm 2 ). Odds Ratio (OR) per standard deviation (SD) increase in salivary midmenstrual 17β-estradiol was 2.49 (95% confidence interval [CI] 1.12-5.53) for having a higher absolute mammographic density (>32.4 cm 2 ). These associations between HDL-C, ovarian steroids and absolute mammographic density were not observed in the middle or highest tertiles of HDL-C. Conclusion : Our findings suggest that low HDL-C, a marker of dyslipidemia, in combination with high levels of either progesterone or estradiol may be associated with higher absolute mammographic density in premenopausal women. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-01-04.