Lung cancer is one of the most common causes of cancer-related death among men and women all over the world. It is characterized by rapid and nearly uncontrolled growth of abnormal cell tissue in the lungs. Since the lungs are involved in the oxygenation of blood, the chances of the cancer cells spreading to other cells and tissues are very high. As of 2004, there are approximately 1.3 million deaths per year due to complications of lung cancer.

Lung cancer is highly correlated to smoking cigarettes. About 91% of lung cancer cases in men and 71% of cases for women are attributed to cigarette smoking. Cigarette smoke contains more than a thousand chemical compounds, and more than sixty of these substances are known carcinogens (substances which may cause cancer). Among these carcinogens, polycyclic aromatic hydrocarbons, benzopyrene, and nitrosamines, are primary causes of abnormal cell growth in the lungs that lead to the development of lung cancer.

The risk of lung cancer is increases the more cigarettes one smokes. Physicians and health care professionals generally measure to the number of cigarettes one smokes as “pack years”. Pack years refers to the number of packs of cigarette smoked in one day multiplied by the number of years that a person has been smoking. For example, if Person A has been smoking two packs of cigarettes every day for the past five years, he has a smoking history of ten pack years.

If for instance, a person decides to stop smoking, his chances of developing cancer gradually decreases as the damaged cells of the lungs are replaced by normal cells and the contaminants and carcinogens are slowly being excreted. For persons who have quit smoking, the risk of developing cancer would be the same as a non-smoker after fifteen years of quitting smoking.