Lung cancer is a disease characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung in a process called metastasis into nearby tissue and, eventually, into other parts of the body. Most cancers that start in lung, known as primary lung cancers, are carcinomas that derive from epithelial cells. Worldwide, lung cancer is the most common cause of cancer-related death in men and women, and is responsible for 1.3 million deaths annually, as of 2004. The most common symptoms are shortness of breath, coughing (including coughing up blood), and weight loss.
The main types of lung cancer are small-cell lung cancer (SCLC), also called oat cell cancer, and non-small-cell lung cancer (NSCLC). The most common cause of lung cancer is long-term exposure to tobacco smoke. Nonsmokers account for 15% of lung cancer cases, and these cases are often attributed to a combination of genetic factors, radon gas, asbestos, and air pollution including secondhand smoke.
Lung cancer may be seen on chest radiograph and computed tomography (CT scan). The diagnosis is confirmed with a biopsy. This is usually performed by bronchoscopy or CT-guided biopsy. Treatment and prognosis depend on the histological type of cancer, the stage (degree of spread), and the patient's general wellbeing, measured by performance status. Common treatments include surgery, chemotherapy, and radiotherapy. NSCLC is sometimes treated with surgery, whereas SCLC usually responds better to chemotherapy and radiation therapy. This is partly because SCLC often spreads quite early, and these treatments are generally better at getting to cancer cells that have spread to other parts of the body.
Survival depends on stage, overall health, and other factors, but overall 14% of people in the United States diagnosed with lung cancer survive five years after the diagnosis.
