While smoking is a risk factor for lung cancer, you do not have to have smoked to get the disease. “About 10% to 20% of lung cancers happen in patients who have never smoked, or who in their lifetime have smoked less than 100 cigarettes,” says Dr. Villena-Vargas. “Diagnoses in these patients are typically due to other risk factors that are not related to smoking.”
These factors include being exposed to radon over a long period of time. Radon, a natural gas that forms in rocks, soil, and water, cannot be detected by sight, taste or smell, but can become trapped in the air inside homes and buildings, according to the Centers for Disease Control and Prevention (CDC). Other factors are secondhand smoke and being around substances or chemicals, such as asbestos, arsenic, diesel, and exhaust, among others.
There is also a risk for lung cancer when there is “a personal or family history, although the reasons are multifactorial and not well understood,” said Dr. Villena-Vargas. In addition, there are populations who are at higher risk for certain types of lung cancer. “For example, in people of East Asian descent, those who have lung cancer are more likely to be female, never smokers, and young. They carry a gene mutation in the epidermal growth factor receptor (EGFR),” he says. EGFR is a protein on cells that helps them grow, but a mutation in the gene for EGFR can make it grow too much, which can cause cancer, states the American Lung Association.