Lung cancer begins when cells in the lung tissue grow abnormally and form a tumor. Some patients develop symptoms early, while others do not realize there is a problem until imaging or testing reveals an abnormality. Although smoking is a major risk factor, lung cancer can also occur in people with other exposure histories or additional medical risks.
Because symptoms often overlap with other pulmonary diseases, a thorough evaluation is necessary. Pulmonary specialists can help determine whether symptoms or test findings need additional investigation.