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近30年来,西方国家结肠癌的发生部位有明显变化。大量资料表明,直肠癌的发生率急骤降低,而与此同时右半结肠癌的发生率明显升高。最近发现,这种变化可能是微量元素硒的缺乏所致,缺乏的原因可为饮食中硒的减少或抗硒物质的增加。一些人推测,结肠癌和直肠癌可能有不同的病因,但目前尚未得到病理及实验的支持。流行病学调查显示:结肠癌的发生涉及环境因素,特别是低纤维、高动物蛋白饮食、牛肉脂肪、啤酒等与结肠癌的高发有关。实验性结肠癌:二甲基肼(DMH)可在大鼠或小
In the past 30 years, there have been significant changes in the occurrence of colon cancer in Western countries. A large number of data indicate that the incidence of rectal cancer has suddenly decreased, and at the same time the incidence of right colon cancer has increased significantly. Recently, it was found that this change may be caused by the lack of trace element selenium. The reason for the lack may be the reduction of selenium in the diet or the increase in anti-selenium substances. Some people speculate that colon cancer and rectal cancer may have different etiologies, but they have not yet been supported by pathology and experiments. Epidemiological investigation shows that the occurrence of colon cancer involves environmental factors, especially low-fiber, high animal protein diets, beef fat, beer, etc., which are related to the high incidence of colon cancer. Experimental Colon Carcinoma: Dimethylhydrazine (DMH) in Rats or Small