The causes and prevention of cancer: gaining perspective.
The causes and prevention of cancer: gaining perspective.
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DOI：
10.1289/ehp.97105s4865
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发表时间：
1997-06
影响因子：
10.4
通讯作者：
中科院分区：
文献类型：
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流行病学研究已经确定了几个可能对降低癌症发病率产生重大影响的因素：减少吸烟，增加水果和蔬菜的消费，以及控制感染。其他因素包括避免强烈的阳光照射、增加身体活动以及减少酒精和可能的红肉消费。许多类型癌症的风险已经可以降低，进一步降低的潜力很大。在美国，所有癌症的死亡率都在下降，如果肺癌（其中90%是由于吸烟）被排除在分析之外。我们回顾了关于癌症原因的研究，并展示了为什么许多癌症是可以预防的。滴滴涕等微量合成化学品是人类癌症的主要促成因素，这一观点没有证据支持，但公众对减少化学品污染的关注和资源分配非常高，部分原因是标准风险评估使用的是从高剂量动物癌症试验的有限数据进行线性外推。这些测试是在最大耐受剂量（MTD）下进行的，通常被误解为意味着低剂量的合成化学品和工业污染物与人类癌症有关。大约一半的化学物质，无论是合成的还是天然的，在如此高的剂量下对啮齿动物都是致癌的。人类饮食中几乎所有的化学物质都是天然的。例如，我们吃的99.99%的杀虫剂是天然存在于植物中的，以抵御昆虫和其他捕食者。在MTD测试的天然杀虫剂中，有一半是啮齿动物致癌物。烹饪食物会产生大量的天然食用化学物质。例如，烘焙咖啡含有超过1000种化学物质：在27种测试中，19种是啮齿动物致癌物。越来越多的证据支持这一观点，即啮齿动物生物测定中阳性结果的高频率是由于在MTD下进行测试，这通常会导致慢性细胞杀伤和随后的细胞增殖-这是一种癌症的风险因素，可限于高剂量。由于默认风险评估使用线性外推法，忽略了高剂量本身的影响，低剂量风险往往被夸大。
Epidemiological studies have identified several factors that are likely to have a major effect on reducing rates of cancer: reduction of smoking, increased consumption of fruits and vegetables, and control of infections. Other factors include avoidance of intense sun exposure, increased physical activity, and reduced consumption of alcohol and possibly red meat. Risks of many types of cancer can already be reduced, and the potential for further reductions is great. In the United States, cancer death rates for all cancers combined are decreasing, if lung cancer (90% of which is due to smoking), is excluded from the analysis. We review the research on causes of cancer and show why much cancer is preventable. The idea that traces of synthetic chemicals, such as DDT, are major contributors to human cancer is not supported by the evidence, yet public concern and resource allocation for reduction of chemical pollution are very high, in part because standard risk assessment uses linear extrapolation from limited data in high-dose animal cancer tests. These tests are done at the maximum tolerated dose (MTD) and are typically misinterpreted to mean that low doses of synthetic chemicals and industrial pollutants are relevant to human cancer. About half the chemicals tested, whether synthetic or natural, are carcinogenic to rodents at such high doses. Almost all chemicals in the human diet are natural. For example, 99.99% of the pesticides we eat are naturally present in plants to ward off insects and other predators. Half of the natural pesticides that have been tested at the MTD are rodent carcinogens. Cooking food produces large numbers of natural dietary chemicals. Roasted coffee, for example, contains more than 1000 chemicals: of 27 tested, 19 are rodent carcinogens. Increasing evidence supports the idea that the high frequency of positive results in rodent bioassays is due to testing at the MTD, which frequently can cause chronic cell killing and consequent cell replacement-a risk factor for cancer that can be limited to high doses. Because default risk assessments use linear extrapolation, which ignores effects of the high dose itself, low-dose risks are often exaggerated.