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KMID : 1231220110020010008
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Journal of the Korean Society for Research on Nicotine and Tobacco
2011 Volume.2 No. 1 p.8 ~ p.22
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Toxicological Mechanisms in Smoking-Induced Cancer: Why Is Smoking Evaluated as One of the Strongest Risk-Factors for Cancer?
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Park Yeong-Chul
Yoon Mi-Sook
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Abstract
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Currently, cigarette smoking accounts for 30% of all cancer cases in the world. The International Agency for Research on Cancer (IARC) identified tobacco smoking as the cause of cancer at more organ sites than any other human carcinogen. Thus, tobacco is the most extreme and strongest example of a systemic carcinogen or a systemic human mutagen. In this paper, the reasons for why smoking is the strongest risk-factor for all cancers were reviewed in terms of toxicological aspects with respect to chemical carcinogenesis. Some 80 carcinogens as well as cocarcinogens, including Group 1 and Group 2 as classified by the IARC, are known to be present in tobacco smoke. Many of these carcinogens, as is the case for the majority of carcinogens, are known to require biotransformation to reactive intermediates (RI) by specific P450 genes. Reactive intermediates interact and induce DNA damage on proto-oncogenes, DNA mismatch-repair genes and tumor-suppressor genes, which are necessary for transforming a normal cell into a cancer cell. Cigarette smoke is also a tumor promoter which does not directly affect DNA but acts in other ways to promote growth. Thus, the reason that cigarette smoking is one of the strongest risk factors with respect to cancer is due to the fact that there are many kinds of chemicals acting as carcinogens and cocarcinogens as well as tumor promoters in many stages of carcinogenesis.
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KEYWORD
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Smoking, Carcinogen, Co-carcinogne, Promoter
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