Lung cancer is a malignant lung tumor. It is characterized by uncontrolled cell growth in tissues of the lung which can spread beyond the lungs by the process of metastasis. There are two main types are small-cell lung carcinoma (SCLC) and non-small-cell lung carcinoma (NSCLC). The most common symptoms are coughing (including coughing up blood), weight loss, shortness of breath, and chest pains.

Tobacco smoking is the greatest risk factor for lung cancer followed by air pollution. Exposure to radon gas, asbestos, second-hand smoke, or other forms of air pollution are other risk factors. Lung cancer usually shows signs only at advanced stages. Therefore, early diagnosis is a challenge. Diagnostic tools for lung cancer include chest radiographs, computed tomography (CT) scans and bronchoscopy. Prevention of lung cancer should focus on quitting smoking and avoiding secondary smoke and improving the air quality indoors and outdoors.