Lung cancer is a disease in which cell growth is uncontrolled in the tissues of the lung. If untreated the growth can spread from the lung into nearby tissue and, eventually, into other parts of the body. The process of the cancer traveling is called metastasis. Two main types of lung cancer are small-cell lung cancer (SCLC), also called oat cell cancer, and non-small-cell lung cancer (NSCLC).
Causes of lung cancer are mostly environmental in nature. Smoking of cigarettes is by far the main cause of lung cancer, leading to 85% of lung cancer cases. This staggering figure is directly caused by the 60 known carcinogens cigarette smoke contains, the most dangerous of these include radioisotopes, nitrosamine, and benzopyrene. In addition to the chemicals cigarette smoke contains, nicotine seems to depress the immune systems response to malignant growths in the tissues exposed to it. However smoking is not the only cause of lung cancer, 15% of cancer victims are non-smokers. Other causes can be attributed to a combination of genetic factors, radon gas, asbestos, and air pollution including secondhand smoke.
In the body, lung cancer is turned on by activation of oncogenes or by the inactivation of tumor suppressor genes. Oncogenes are genes that are believed to make people more susceptible to cancer and Proto-oncogenes are believed to turn into oncogenes when exposed to particular carcinogens.
The most common early symptoms are shortness of breath, coughing and weight loss.
An ongoing cough or any of these symptoms should prompt further investigation. Patients with chest infections may have an underlying lung cancer so if symptoms do not improving their chest may need further investigation. Some patients who have had a chest x-ray because of a chest infection may have to do several over time to there was not a cancer hidden by infection.
Progressive symptoms that may suggest lung cancer include hemoptysis (coughing...