Loma Linda University, Loma Linda, California, USA.
Nutr Cancer. 2009;61(6):792-8. doi: 10.1080/01635580903285015.
There is a large variation in breast cancer incidence and mortality rates worldwide. Migration studies have indicated that this variation is primarily the result of lifestyle influences. Although there has been much research conducted, definitively identifying dietary factors that impact breast cancer risk has proven difficult. In part this may be because most clinical and epidemiologic studies have focused on adult dietary exposure. However, evidence suggests that childhood and/or adolescence is the period of life when the breast is most sensitive to dietary influences. Further, the available epidemiologic and animal data suggest that early soy intake reduces breast cancer risk. Soy foods are unique dietary sources of isoflavones, diphenolic compounds that exert estrogen-like effects under certain experimental conditions. The protection effects of soy may result from the soybean isoflavones stimulating differentiation of the breast in much the same way that the elevated estrogen levels do during pregnancy. More specifically, in rats, the primary isoflavone genistein reduces mammary tumorigenesis and increases mammary tissue differentiation by leading to a reduction in the number of terminal end buds (TEB) and an increase in the number of differentiated lobules. There is need and justification for continued investigation of the early soy intake hypothesis, particularly to determine the cellular targets of soy action and to identify the signaling pathways mediating the effects on mammary gland morphology and susceptibility to breast cancer.
全世界的乳腺癌发病率和死亡率存在很大差异。移民研究表明，这种差异主要是生活方式影响的结果。尽管已经进行了大量研究，但要明确确定影响乳腺癌风险的饮食因素一直很困难。部分原因可能是大多数临床和流行病学研究都集中在成人的饮食暴露上。然而，有证据表明，儿童期和/或青春期是乳房对饮食影响最敏感的时期。此外，现有的流行病学和动物数据表明，早期摄入大豆可降低乳腺癌风险。大豆食品是异黄酮的独特饮食来源，异黄酮是在某些实验条件下具有雌激素样作用的二酚类化合物。大豆的保护作用可能是由于大豆异黄酮以与妊娠期间升高的雌激素水平大致相同的方式刺激乳房的分化。更具体地说，在大鼠中，主要的异黄酮染料木黄酮通过减少终末芽（TEB）的数量和增加分化小叶的数量，减少乳腺肿瘤发生并增加乳腺组织分化。需要并证明有理由继续研究早期大豆摄入假说，特别是为了确定大豆作用的细胞靶标，并确定介导对乳腺形态和乳腺癌易感性影响的信号通路。
