Lung cancer is the leading cause of cancer death globally, with nearly as many Americans dying from it as from prostate, breast, and colon cancer combined. In 2010, it was estimated that 239,320 new cases and 161,250 deaths occurred in the U.S. Globally, it is the most common cancer and the leading cause of cancer death. The 5-year survival rate in the U.S. is 15.6%, with significant improvements in survival for other cancers not yet achieved for lung cancer. Lung cancer incidence has increased in developing countries, with 49.9% of cases now occurring there. In the U.S., it ranks second in both genders, with 115,060 new cases in men and 106,070 in women. The age-adjusted incidence rate is 62 per 100,000 in the U.S., with higher rates in men. Lung cancer is the leading cause of cancer death in men and the second leading cause in women globally. The 5-year survival rate for lung cancer in the U.S. is 15.6%, with localized disease having a 52% survival rate and distant metastasis a 3.6% survival rate. Tobacco smoking is the principal risk factor for lung cancer, with cigarette smoking increasing the risk by 9- to 10-fold for men and 20-fold for heavy smokers. The Surgeon General of the U.S. has confirmed that cigarette smoking is the major cause of lung cancer. Cigarette smoke contains over 4000 chemical constituents, including carcinogens like polycyclic aromatic hydrocarbons (PAHs) and tobacco-specific N-nitrosamines (TSNAs), which can bind to DNA and cause mutations. The risk of lung cancer is proportional to the quantity of cigarette consumption, with heavy smokers having a 30% risk compared to less than 1% for nonsmokers. Smoking rates have declined in the U.S., but the number of smokers is still high, with 20.6% of American adults smoking. Cigar and pipe smoking also increase lung cancer risk, though less than cigarette smoking. Never smokers account for 25% of all lung cancer cases globally, with 15% in men and up to 53% in women. In the U.S., 19% of lung cancer in women and 9% in men occur in never smokers. The incidence of lung cancer in never smokers varies geographically, with higher rates in certain regions. Adenocarcinoma is more common in never smokers than in smokers, and it is becoming more common even among smokers due to deeper inhalation of lower-tar cigarettes. Lung cancer in never smokers is associated with factors like secondhand smoke, radonLung cancer is the leading cause of cancer death globally, with nearly as many Americans dying from it as from prostate, breast, and colon cancer combined. In 2010, it was estimated that 239,320 new cases and 161,250 deaths occurred in the U.S. Globally, it is the most common cancer and the leading cause of cancer death. The 5-year survival rate in the U.S. is 15.6%, with significant improvements in survival for other cancers not yet achieved for lung cancer. Lung cancer incidence has increased in developing countries, with 49.9% of cases now occurring there. In the U.S., it ranks second in both genders, with 115,060 new cases in men and 106,070 in women. The age-adjusted incidence rate is 62 per 100,000 in the U.S., with higher rates in men. Lung cancer is the leading cause of cancer death in men and the second leading cause in women globally. The 5-year survival rate for lung cancer in the U.S. is 15.6%, with localized disease having a 52% survival rate and distant metastasis a 3.6% survival rate. Tobacco smoking is the principal risk factor for lung cancer, with cigarette smoking increasing the risk by 9- to 10-fold for men and 20-fold for heavy smokers. The Surgeon General of the U.S. has confirmed that cigarette smoking is the major cause of lung cancer. Cigarette smoke contains over 4000 chemical constituents, including carcinogens like polycyclic aromatic hydrocarbons (PAHs) and tobacco-specific N-nitrosamines (TSNAs), which can bind to DNA and cause mutations. The risk of lung cancer is proportional to the quantity of cigarette consumption, with heavy smokers having a 30% risk compared to less than 1% for nonsmokers. Smoking rates have declined in the U.S., but the number of smokers is still high, with 20.6% of American adults smoking. Cigar and pipe smoking also increase lung cancer risk, though less than cigarette smoking. Never smokers account for 25% of all lung cancer cases globally, with 15% in men and up to 53% in women. In the U.S., 19% of lung cancer in women and 9% in men occur in never smokers. The incidence of lung cancer in never smokers varies geographically, with higher rates in certain regions. Adenocarcinoma is more common in never smokers than in smokers, and it is becoming more common even among smokers due to deeper inhalation of lower-tar cigarettes. Lung cancer in never smokers is associated with factors like secondhand smoke, radon