Lung cancer is the second most common cancer in both men and women (both small cell and non-small cell). In men, only prostate cancer is more common, while breast cancer is more prevalent in women. The most common age group for people diagnosed with lung cancer is 65 and older; only a tiny number of patients are under the age of 45. On average, individuals receive their diagnosis at the age of 70. 
Overall, the chance that a man would get lung cancer at some point in his life is around 1 in 15; for a woman, it’s about 1 in 17. These figures include both smokers and non-smokers. 
Is Lung Cancer Very Common?
Lung cancer accounts for almost 25% of all cancer deaths in both men and women. More people die of lung cancer each year than from colon, breast, or prostate malignancies combined. 
However, the number of new lung cancer cases is declining, in part due to smoking cessation. There is also a reduction in the number of lung cancer deaths, which is also due to individuals quitting smoking and medical progress in early detection and treatment.
Can Non-smokers Develop Lung Cancer?
Despite the general reduction in lung cancer rates, the rate of lung cancer in non-smokers has been noted to be increasing.  Although smoking causes the majority of lung cancers, about 16 percent of women and 11 percent of men who die from lung cancer have never smoked or used tobacco products.  There have been several suspected risk factors in non-smokers, but none are known to be directly causative at this time.
Some of the possible causes include: 
Second-hand smoke: multiple studies have suggested that 15-35 percent of lung cancer in non-smokers is due to second-hand smoke exposure.
Environmental exposures: linked to lung cancer by several studies, some known exposures include asbestos, chromium, and arsenic.
Radon gas: is a potential risk. Radon is known to be present in soil, rock, and groundwater and due to this can accumulate in homes. Although controversial, exposure to radon within homes may play a role in the development of lung cancer in non-smokers.
Genetic factors: many studies have shown that those with a family history of lung cancer are at increased risk.