Lung cancer is considered a silent killer because there are no early warning signs.
By the time it's detected, lung cancer is typically the size of an orange. More than 160,000 people die of lung cancer every year in the United States, and it is the leading cause of cancer mortality in both men and women, according to the American Lung Association. Those who quit smoking decrease their risk of getting lung cancer, but even after 20 years, smokers and former smokers remain at more than twice the risk of developing lung cancer as non-smokers. Those at risk for developing lung cancer were defined by the study as men and women 60 years or older who smoked at least a pack of cigarettes every day for at least 10 years, or two packs a day for 5 years. In phase two, researchers are reporting results of 808 smokers and former smokers based on their multiple annual repeat screenings, a total of 1,398 person-years of annual CT screening.