我们所吃的某些食物中或许有还未发现的具有抗癌作用的化合物。大豆异黄酮是大豆中主要成分，近年来研究表明该化合物具有抗雌激素活性，发挥抗肿瘤作用。
但最新，发表在由美国癌症研究协会出版的杂志Cancer Prev Res上的一篇研究论文证实：大豆中主要黄酮类物质--大豆异黄酮并不能抑制乳腺癌细胞的增殖。
在由西北大学Robert H. Lurie研究中心的外科医生--Seema A. Khan, M.D带领开展的这项随机临床试验中，研究人员随机给98名女性乳腺癌患者服用混合型大豆异黄酮补充剂或是安慰剂。
98名乳腺癌患者在服用大豆异黄酮或是安慰剂6个月后，研究者检测了患者体内一种被证实是癌细胞生长的蛋白标志物--Ki-67的水平。
结果发现：服用大豆异黄酮的乳腺癌患者与服用安慰剂的乳腺癌患者体内Ki-67的水平并没有差异。但未绝经的乳腺癌女性患者体内， Ki-67的水平从1.71增加到了2.18，这一结果提示了大豆异黄酮补充剂有可能存在阴性作用，即有可能促进肿瘤细胞的生长。
研究人员表示：虽然大豆异黄酮主要来之于大豆食物中，但这并不表示我们食用大豆能带来类似大豆异黄酮补充剂的功效。并且使用大豆异黄酮补充剂能否抑制乳腺癌细胞的增殖仍没有定论。(生物谷 Bioon.com)
doi:10.1158/1940-6207.CAPR-11-0251
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Soy Isoflavone Supplementation for Breast Cancer Risk Reduction: A Randomized Phase II Trial
Seema A. Khan1, Robert T. Chatterton2, Nancy Michel4, Michelle Bryk1, Oukseub Lee1, David Ivancic1, Richard Heinz1, et al.
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. One hundred and twenty-six consented women underwent a random fine-needle aspiration (rFNA); those with 4,000 or more epithelial cells were randomized to a double-blind 6-month intervention of mixed soy isoflavones (PTIG-2535) or placebo, followed by repeat rFNA. Cells were examined for Ki-67 labeling index and atypia. Expression of 28 genes related to proliferation, apoptosis, and estrogenic effect was measured using quantitative reverse transcriptase PCR. Hormone and protein levels were measured in nipple aspirate fluid (NAF). All statistical tests were two-sided. Ninety-eight women were evaluable for Ki-67 labeling index. In 49 treated women, the median Ki-67 labeling index 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 labeling index 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 of 28 genes within the soy, but not the control group, without significant between-group differences. Plasma genistein values showed excellent compliance. A 6-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.
