吸烟有害健康（二）
So what are the risks? Here's what tobacco's critics say:
CANCER
The Centers for Disease Control and Prevention says cigarette smoking is responsible for 151,322 cancer deaths annually in the United States. Most of those――116,920――are from lung cancer. The CDC says men who smoke are 22 times more likely to die from lung cancer than non-smokers. Women who smoke are 12 times more likely to die from the disease.
Statistical studies have long shown that people who don't smoke live longer than people who do and scientists have seen statistically the correlation between smoking and incidences of lung cancer since the 1950s.
But a study earlier this year by Gerd Pfeifer of the Beckman Research Institute pinpointed specific carcinogens in cigarette smoke that target parts of a gene already known to be prominent in some cancers.
Pfeifer wrote in Science that cigarette smoke causes changes in the gene p53, which protects against cancer when normal but promotes cancer growth when mutated .
Another study, published by the American Cancer Society, said that low-tar cigarettes offered no relief from the potential of cancer, and in fact were responsible for a type of cancer that reaches deeper into lung tissue.
Other cancers are also affected by cigarette smoke. An American Cancer Society researcher reported earlier this year that smoking increased men's risk of dying of prostate cancer, while other studies have linked tobacco use to increased risk of other cancers, including throat, breast and bowel cancer.
那么吸烟究竟有什么危害呢?还是听听烟草批评家们的说法：
癌症
疾病防治中心说，吸烟是导致美国每年151322位癌症患者死亡的罪魁祸首。这些死亡者中的大多数――116990人是死于肺癌。疾病防治中心认为，男性烟民死于肺癌的可能性是非吸烟者的22倍。女性烟民死于肺癌的可能性是非吸烟者的 12倍。
统计数据研究早就表明，不吸烟的人比烟民长寿，而且自20世纪50年代以来，科学家们通过统计资料，已经发现了吸烟和肺癌发病率之间的相互关系。
而今年早些时候，贝克曼研究所的格尔德・普法伊费尔所作的一项研究确切地指出了卷烟烟雾中固有的致癌物，这些致癌物袭击的目标是一种基因的某些部分，人们已经发现，这种基因在一些癌症中很突出。 普法伊费尔在《科学》杂志上写道，吸烟使p53基因发生改变，这种基因在正常情况下起着防癌的作用，但在发生突变时，就会加快癌症的发展。
美国癌症协会发表的另一份研究报告说，尼古丁含量低的卷烟并不能减少患癌症的可能性，它们实际上是引起一种进入到肺组织深层的癌症的罪魁祸首。
而其他的癌症也受吸烟的影响。今年年初，美国癌症协会的一份研究报告表明，吸烟使男性死于前列腺癌的危险增加了，而其他的一些研究把吸烟同患上其他癌症(包括喉癌、乳腺癌和结肠癌)的危险的增加联系到了一起。
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