The first official statement on the relationship between cigarette smoking and cancer was provided in the Report of the Advisory Committee to the Surgeon General of the U.S. Public Health Service in 1964. In this report, it concluded that: Cigarette smoking is causally related to lung cancer in man; the magnitude of the effect of cigarette smoking far outweighs all other factors.
The risk of developing lung cancer increases with the duration of smoking and the number of cigarettes smoked per day and is diminished by discontinuing smoking. The capacity for developing cancers depends on the nicotine content of the tar.
Nicotine itself has not been proven to be carcinogenic in human but it has been found to be a co-carcinogenic compound. Burning of tobacco will convert nicotine to “tobacco-specific nitrosamines” which are highly carcinogenic. This is conformable with the reports by the National Cancer Institute (1979) which stated that “cigarette smoke and tobacco tar act as complete carcinogens, since no additional compounds or steps are necessary to induce malignant changes in a variety of animal systems” .
The relationship between cigarette smoking and the development of cancers does not disappear with the introduction of low “tar”, low nicotine cigarettes. A report given by the Surgeon General concluded that these low tar and nicotine cigarettes had cut down lung cancer rates. However, these smokers still had higher lung cancer rates than nonsmokers.
Lung cancer is not only cancer induced by cigarette smoking. The occurrence of laryngeal cancer and cancers on the oral cavity, esophagus, urinary bladders are a few of the other examples on the list. Carbon monoxide and tar, which are a mixture of compounds deriving from the burning of tobacco, are two other hazardous products of cigarette smoking. Carbon monoxide reduces the oxygen-carrying capacity of the blood and results in the increase of coronary blood flow.