Cigarette smoking has been identified as the second leading risk factor for death from any cause worldwide. In 2000, an estimated 4.83 million deaths were attributed to cigarette smoking globally, with nearly half occurring in the developing world. With a population of 1.3 billion, China is the world's largest producer and consumer of tobacco and bears a large proportion of deaths attributable to smoking worldwide.
Lung cancer is the leading cause of death among smokers. In 2007, there were an estimated 213 380 new lung and bronchus cancer cases and 160 390 people died of this disease in the USA. Epidemiological studies have demonstrated that most cases of lung cancer are directly attributable to cigarette smoking. Only 5-10% of all of the lung cancers occur in patients without a prior history of cigarette smoking . Compared to non-smokers, smokers have a 10 fold greater risk of dying from lung cancer and in heavy smokers this risk increases by 15-25 folds. Although associations between cigarette smoking and lung cancer are well documented, surprisingly little is known about the mechanistic basis of smoking-related lung cancer at the cellular level. This is due, in part, to the fact that cigarette smoke is a complex and dynamic mixture of more than 4,000 individual chemical constituents. Cigarette smoke has been shown to have multiple effects on gene expression primarily, the expression of xenobiotic-metabolizing, redox-regulating genes, tumor suppressor genes, oncogenes, and genes involved in the regulation of inflammation .
Nicotine is the chemical in cigarettes that makes people addictive. Higher levels of nicotine in a cigarette can make it harder to quit smoking. A report by the Massachusetts Department of Health found that the amount of nicotine in cigarettes has steadily increased over the last 6 years. Higher nicotine levels were found in all cigarette categories, including "light" brands. In addition to nicotine, cigarette contains over 19 known cancer-causing chemicals (most are collectively known as "tar") and more than 4,000 other chemicals.
-aadautech, a cancer drug discovery and therapeutics blog.