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Tobacco smoking is a major cause of lung cancer. Carcinogens in tobacco smoke can damage the cells in the lungs, which may lead to the development of lung cancer.
More than fifty chemical compounds in tobacco smoke have been recognized as known or probable human carcinogens, some of which may be formed during or smoking and some which may exist naturally in tobacco. Several groups of carcinogens in tobacco smoke are related to lung cancer, including polycyclic aromatic hydrocarbons (PAHs), aromatic amines, benzene, hydrazine, and vinyl chloride.
Smoking destroy bronchial and lung epithelium which leads to lung cancer. A very strong association between cigarette smoking and lung cancer has been consistently observed in studies done since the early 1950s.
These studies have shown that cigarette smoking precedes lung cancer occurrence. It has been estimated that cigarette smokers have a ten-fold higher risk of lung cancer, in comparison with nonsmokers.
With the increased number of cigarettes smoked per day, the risk is increased.
Beginning to smoke at an early age is also related to an increased risk, and the lung cancer risk declines with an increased duration of cessation.
The percentage of reduction in risk after quitting smoking depends on the duration of exposure to smoking. The observed relationship between cigarette smoking and the risk of lung cancer is consistent with different study designs and in studies of different populations all over the world. Over eighty-five percent of deaths from lung cancer can be attributed to cigarette smoking.
Smoking of other tobacco products, such as cigar and pipe smoking, is also associated with an increased risk of lung cancer. Like cigarette smoking, the risk of lung cancer is increased with the frequency and years of cigar and pipe smoking.
The promotion of smoking cessation is the most cost-effective tool against lung and other smoking-related cancers and diseases.