According to American Cancer Society statistics, there will be 232,270 new cases of lung cancer in 2008, accounting for approximately 15% of cancer diagnoses. The likelihood of developing lung cancer is 1 in 2500 in men younger than 39 years of age and 1 in 15 in men between the ages of 60 and 79 years.
The vast majority of patients with lung cancer will still die of the disease. It is estimated that 166,280 patients will die of lung cancer in 2008, accounting for 31% of all cancer deaths in men and 26% of cancer deaths in women. Among women, the rate of deaths from lung cancer remains high. Since 1987, more women have died from lung cancer than from breast cancer. Despite an enormous effort to find effective therapies for lung cancer, the overall 5-year survival remains only 15%. The high mortality rate and low 5-year survival rate are largely the result of an inability to diagnose lung cancer at an early stage, when it is still potentially curable. Only 15% of lung cancers are diagnosed at this early stage. The uniformly poor results obtained with current therapies are a strong argument for the inclusion of all possible patients into clinical trials.
Smoking is by far the most common cause of lung cancer. Approximately 85% to 90% of lung cancer cases can be attributed directly to tobacco smoking. The risk of lung cancer is directly related to the length of time a person smokes, the number of cigarettes smoked per day, the age at which a person starts smoking, and the amount of tar contained in the cigarettes. The risk of developing lung cancer is 9- to 10-fold higher in an average smoker and up to 25-fold higher for a heavy smoker. However, not all tobacco smokers develop lung cancer. This may be attributable to differences in an individual's inherited predisposition to cancer development. There is also evidence that nonsmokers exposed to tobacco smoke (passive smokers) have an increased risk of developing lung cancer. It has been estimated that up to 25% of lung cancers in nonsmokers are caused by passive smoking. The risk of lung cancer declines steadily once a person stops smoking, but it takes up to 15 to 20 years for the risk to return to the level of nonsmokers. However, it never reaches this level if they had smoked two packs per day or more.
Other factors reported to cause lung cancer include occupational exposure to arsenic, asbestos, nickel, uranium, chromium, silica, beryllium, and diesel exhaust. Dietary deficiency of vitamins A, C, and E, retinoids, carotenoids, and selenium, and air pollution, lung scars, and oncogenes have all been implicated in the causation of lung cancer. Asbestos is the most common occupational cause of lung cancer and increases the risk of ...