Background: Both the absolute and the percent of mammographic density are strong and independent risk factors for breast cancer. Previously, we showed that the association between mammographic density and breast cancer risk tended to be weaker in African American than in White U.S. women. Because African American women have a larger breast size, we assessed whether the association between mammographic density and breast cancer was less apparent in large than in small breasts. Methods: We assessed mammographic density on mammograms from 348 African American and 507 White women, 479 breast cancer patients and 376 control subjects, from a case-control study conducted in Los Angeles County. We estimated odds ratios (OR) for breast cancer with increasing mammographic density, and the analyses were stratified by mammographic breast area.

Aims: Certain phytoestrogens, such as lignans, may protect against developing breast cancer. Enterolactone is a lignan metabolite produced by the intestinal flora from dietary precursors such as whole grains, vegetables, and fruits. Enterolactone has been shown to have weak estrogenic and antiestrogenic properties. We decided to examine the association between plasma levels of enterolactone and mammographic density, a biomarker for breast cancer risk. Methods: We included data from postmenopausal women ages 55 and older who participated in a cross-sectional mammogram study in Tromsø, Norway. Mammograms, plasma enterolactone measurements, as well as information on anthropometric and hormonal/reproduction factors were available on 616 women. We assessed mammographic density using a previously validated computer-assisted method. We estimated correlation coefficients and conducted multiple regression analyses. Results: Mean mammographic density increased slightly across quartiles of enterolactone; the women in the highest quartile had, on average, 3.1% (absolute difference) higher percentage mammographic density compared with the lowest quartile (P trend < 0.01). After adjustment for age, body mass index, number of full-term pregnancies, age at first birth, and use of postmenopausal hormone therapy, the mean difference in density was reduced to 2.0% (P trend = 0.05). Results were similar when restricted to the 454 current hormone nonusers. The fully adjusted statistical model explained 28.3% of the total variability in mammographic percentage density, with body mass index contributing 18.2% and enterolactone only 0.9%. Conclusion: In our study, higher levels of enterolactone were associated with slightly higher percentage mammographic density. Our results suggest that if higher enterolactone levels reduce the risk of developing breast cancer in postmenopausal women, then this effect is not through lowering mammographic density. (Cancer Epidemiol Biomarkers Prev 2005;14(9):2154 -9)

Our study suggests that the effect of E2/NETA regimens on mammographic density could be at least as detrimental to the breast tissue as several other estrogen + progestin regimens. Our results suggest that both low- and high-dose E2/NETA influence mammographic density, but there were some indications in our analyses that the effect of low-dose E2/NETA could be slightly lower than that of the older high-dose regimen.

Introduction Obesity has been linked to increased risk of breast cancer in postmenopausal women. Increased peripheral production of estrogens has been regarded as the main cause for this association, but other features of increased body fat mass may also play a part. Leptin is a protein produced mainly by adipose tissue and may represent a growth factor in cancer. We examined the association between leptin plasma levels and mammographic density, a biomarker for breast cancer risk.