Basic and Epidemiological study for the carcinogenic role of obesity and nutritional factors in breast and colon cancers

最近，日本女性中乳腺癌和结肠癌的发病率正在上升。由于这些癌症被认为是肥胖和饮食相关的疾病，我们通过体内、体外和流行病学方法调查了乳腺癌与内脏脂肪、肥胖和饮食因素的关系。内脏性肥胖模型大鼠口服甲烷磺酸乙酯（EMS） 40周后未产生任何肿瘤，而对照组大鼠16只大鼠中有2只大鼠产生肿瘤。染料木黄酮（genstein，一种雌激素活性较弱的植物化学物质）在饲喂低至高浓度染料木黄酮饮食的WKA大鼠中，并没有抑制ems诱导的激素依赖性肿瘤的发生率。一项病例对照研究表明，在绝经后的日本妇女中，油和植物脂的摄入与乳腺癌风险升高有关，但与大豆摄入量无关。这些结果表明大豆异黄酮可能不会降低绝经后妇女患乳腺癌的风险。

Incidence of breast and colon cancer is increasing recently among Japanese women. As these cancers are considered to be obesity- and diet-linked diseases, we have investigated the association of breast carcinogenesis with visceral fat obesity and dietary factors through in vivo, in vitro, and epidemiological approaches. Model rats for visceral obesity did not produce any tumor 40 weeks after oral administration of ethylmethane sulphonate (EMS), while a control rats produced tumors in 2 rats out of 16 rats. Genistein (GEN), a phytochemical with weak estrogenic activity, did not suppress the incidence of EMS-induced hormone-dependent tumor in WKA rats fed on diets with low to high concentrations of GEN. A case-control study suggests that intakes of oil and plant lipids were associated with elevated risk for breast cancer, but not with Soybean intake in postmenopausal Japanese women. These results suggest that Soybean isoflavone may not reduce the risk of breast cancer for postmenopausal women.