一項大規(guī)模的日本人研究發(fā)現(xiàn),，大豆異黃醇無法對抗末期的攝護腺癌,。
在這項最大型的研究中，審查日本傳統(tǒng)富含大豆的飲食與日本人攝護腺癌發(fā)生率的相關性,，結果得到了矛盾的結論：異黃醇的攝取量可減少局部的攝護腺癌風險,，但是反而會增加末期攝護腺癌的風險,。
這項共包含43,509名男性的前瞻性研究,，發(fā)表于3月號的Cancer Epidemiology, Biomarkers & Prevention中，研究結果異黃醇對于攝護腺癌發(fā)展的影響,，可能會依不同的疾病階段而異,。
其中一種可能的解釋是，異黃醇可能會延遲潛伏的攝護腺癌發(fā)生,，一旦腫瘤不再表現(xiàn)雌性激素受體且發(fā)展至末期,，異黃醇就無法保護男性免于末期的攝護腺癌，甚至可能會增加惡化的風險,，因為異黃醇會減少血清中的睪固酮,。
另外一種可能是，末期和局部化的攝護腺癌可能屬于不同的腫瘤亞型，所以對于異黃醇的反應不同,。
目前的研究結果還無法理解末期和局部化的攝護腺癌對于異黃醇的反應為何不一樣,，因此研究人員建議，日本男性還是可以繼續(xù)依照原本的飲食習慣,，但是盡量避免服用異黃醇補充劑,。
(資料來源 : Bio.com)
部分英文原文：
Cancer Epidemiology Biomarkers & Prevention 16, 538-545, March 1, 2007. Published Online First March 2, 2007;
doi: 10.1158/1055-9965.EPI-06-0517
Soy Product and Isoflavone Consumption in Relation to Prostate Cancer in Japanese Men
Norie Kurahashi, Motoki Iwasaki, Shizuka Sasazuki, Tetsuya Otani, Manami Inoue, Shoichiro Tsugane Japan Public Health Center–Based Prospective Study Group
Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan
Requests for reprints: Shoichiro Tsugane, Epidemiology and Prevention Division, Research Center for Cancer Prevention and Screening, National Cancer Center, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045 Japan. Phone: 81-3-3542-2511; Fax: 81-3-3547-8578. E-mail: [email protected]
The incidence of prostate cancer is much lower in Asian than Western populations. Environmental factors, such as dietary habits, may play a major role in the causation of prostate cancer. Although isoflavones have been suggested to show a preventive effect against prostate cancer in animal experiments, the results of epidemiologic studies are inconsistent. Here, we conducted a population-based prospective study in 43,509 Japanese men ages 45 to 74 years who generally have a high intake of isoflavones and low incidence of prostate cancer. Participants responded to a validated questionnaire, which included 147 food items. During follow-up from 1995 through 2004, 307 men were newly diagnosed with prostate cancer, of which 74 cases were advanced, 220 cases were organ localized, and 13 cases were of an undetermined stage. Intakes of genistein, daidzein, miso soup, and soy food were not associated with total prostate cancer. However, these four items decreased the risk of localized prostate cancer. In contrast, positive associations were seen between isoflavones and advanced prostate cancer. These results were strengthened when analysis was confined to men ages >60 years, in whom isoflavones and soy food were associated with a dose-dependent decrease in the risk of localized cancer, with relative risks for men in the highest quartile of genistein, daidzein, and soy food consumption compared with the lowest of 0.52 [95% confidence interval (95% CI), 0.30-0.90], 0.50 (95% CI, 0.28-0.88), and 0.52 (95% CI, 0.29-0.90), respectively. In conclusion, we found that isoflavone intake was associated with a decreased risk of localized prostate cancer. (Cancer Epidemiol Biomarkers Prev 2007;16(3):538–45)
