Background Soy isoflavone consumption may protect against breast cancer development. We conducted a Phase IIB trial of soy isoflavone supplementation, to examine its effect on breast epithelial proliferation and other biomarkers in the healthy high risk breast. Methods 126 consented women underwent a random fine needle aspiration (rFNA); those with ≥ 4000 epithelial cells were randomized to a double-blind six-month intervention of mixed soy isoflavones (PTIG-2535) or placebo, followed by repeat rFNA. Cells were examined for Ki-67 labeling index (Ki-67 LI), and atypia. Expression of 28 genes related to proliferation, apoptosis and estrogenic effect was measured using quantitative RT-PCR. Hormone and protein levels were measured in nipple aspirate fluid (NAF). All statistical tests were 2-sided. Results 98 women were evaluable for Ki-67 LI. In 49 treated women, the median Ki-67 LI was 1.18 at entry and 1.12 post-intervention, whereas in 49 placebo subjects it was 0.97 and 0.92 (p for between-group change 0.32). Menopausal stratification yielded similar results between groups, but within premenopausal soy-treated women, Ki-67 LI increased from 1.71 to 2.18 (p=0.04). We saw no treatment effect on cytologic atypia or NAF parameters. There were significant increases in the expression of 14/28 genes within the soy, but not the control group, without significant between-group differences. Plasma genistein values demonstrated excellent compliance. Conclusions A six-month intervention of mixed soy isoflavones in healthy, high risk adult western women did not reduce breast epithelial proliferation, suggesting a lack of efficacy for breast cancer prevention, and a possible adverse effect in premenopausal women.

Public transportation ads have the potential to generate numerous minority contacts and consents at a reasonable cost within an urban setting. Combined with traditional methods of recruitment, this method can lead to timelier study completion and increased minority accrual. Future research should prospectively track recruitment and costs in order to better assess the cost-effectiveness of recruitment methods used to target minority populations.