Lung cancer is a cancer that originates in the lungs. More than 220,000 Americans are diagnosed with lung cancer each year. And lung cancer causes more than 157,000 deaths annually, making it the leading cause of cancer death in men and women. Those most at risk are people aged 50 or older, who have a history of cigarette, cigar, or pipe smoking. However, people who have never smoked can also develop the disease due to past lung infections, environmental factors, and genetic predisposition.