Lung cancer is a disease of uncontrolled cell growth in tissues of the lung. This growth may lead to metastasis, which is invasion of adjacent tissue and infiltration beyond the lungs. The vast majority of primary lung cancers are carcinomas of the lung, derived from epithelial cells. Lung cancer, the most common cause of cancer-related death in men and the second most common in women (after breast cancer),[1] is responsible for 1.3 million deaths worldwide annually.[2] The most common symptoms are shortness of breath, coughing (including coughing up blood), and weight loss.[3]
The main types of lung cancer are small cell lung carcinoma and non-small cell lung carcinoma. This distinction is important, because the treatment varies; non-small cell lung carcinoma (NSCLC) is sometimes treated with surgery, while small cell lung carcinoma (SCLC) usually responds better to chemotherapy and radiation.[4] The most common cause of lung cancer is long-term exposure to tobacco smoke.[5] The occurrence of lung cancer in nonsmokers, who account for as many as 15% of cases [6], is often attributed to a combination of genetic factors,[7][8] radon gas,[9] asbestos,[10] and air pollution,[11][12][13] including secondhand smoke.[14][15]
Lung cancer may be seen on chest x-ray and computed tomography (CT scan). The diagnosis is confirmed with a biopsy. This is usually performed via bronchoscopy or CT-guided biopsy. Treatment and prognosis depend upon the histological type of cancer, the stage (degree of spread), and the patient's performance status. Possible treatments include surgery, chemotherapy, and radiotherapy. With treatment, the five-year survival rate is 14%.[3]
In modern parlance, a gun is a projectile weapon using a hollow, tubular barrel with a closed end—the breech—as the means for directing the projectile as well as other purposes—an expansion chamber for propellant, stabilizing the projectile's trajectory, aiming, etc.—and assumes a generally flat trajectory for the projectile.
The generic form of a trigger initiated, hand-held, and hand-directed tool with an extending bore has additionally been applied to implements resembling guns in either form or concept. Examples of this application include items such as staple guns, nail guns, and glue guns. Occasionally, this tendency is ironically reversed, such as the case of the American M3 submachine gun which carries the nickname "Grease Gun".
