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Lung cancer, also known as carcinoma of the lung or pulmonary carcinoma, is a malignant lung tumor characterized by uncontrolled cell growth in tissues of the lung. If left untreated, this growth can spread beyond the lung by process of metastasis into nearby tissue or other parts of the body. Most cancers that start in the lung, known as primary lung cancers, are carcinomas that derive from epithelial cells. The main primary 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.〔 The vast majority (80–90%) of cases of lung cancer are due to long-term exposure to tobacco smoke.〔〔 About 10–15% of cases occur in people who have never smoked.〔 These cases are often caused by a combination of genetic factors〔 and exposure to radon gas,〔 asbestos,〔 or other forms of air pollution,〔 including second-hand smoke.〔〔 Lung cancer may be seen on chest radiographs and computed tomography (CT) scans. The diagnosis is confirmed by biopsy〔 which is usually performed by bronchoscopy or CT-guidance. Treatment and long-term outcomes depend on the type of cancer, the stage (degree of spread), and the person's overall health, 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 radiotherapy. Overall, 16.8% of people in the United States diagnosed with lung cancer survive five years after the diagnosis,〔(【引用サイトリンク】 url=http://seer.cancer.gov/statfacts/html/lungb.html )〕 while outcomes on average are worse in the developing world. Worldwide, lung cancer is the most common cause of cancer-related death in men and women, and was responsible for 1.56 million deaths annually, as of 2012. ==Signs and symptoms== Signs and symptoms which may suggest lung cancer include:〔 * Respiratory symptoms: coughing, coughing up blood, wheezing or shortness of breath * Systemic symptoms: weight loss, fever, clubbing of the fingernails, or fatigue * Symptoms due to the cancer mass pressing on adjacent structures: chest pain, bone pain, superior vena cava obstruction, difficulty swallowing If the cancer grows in the airways, it may obstruct airflow, causing breathing difficulties. The obstruction can lead to accumulation of secretions behind the blockage, and predispose to pneumonia.〔 Depending on the type of tumor, paraneoplastic phenomena—symptoms not due to the local presence of cancer—may initially attract attention to the disease.〔 In lung cancer, these phenomena may include Lambert–Eaton myasthenic syndrome (muscle weakness due to autoantibodies), hypercalcemia, or syndrome of inappropriate antidiuretic hormone (SIADH, abnormally concentrated urine and diluted blood). Tumors in the top of the lung, known as Pancoast tumors, may invade the local part of the sympathetic nervous system, leading to Horner's syndrome (dropping of the eyelid and a small pupil on that side), as well as damage to the brachial plexus.〔 Many of the symptoms of lung cancer (poor appetite, weight loss, fever, fatigue) are not specific.〔 In many people, the cancer has already spread beyond the original site by the time they have symptoms and seek medical attention.〔 Symptoms that suggest the presence of metastatic disease include weight loss, bone pain and neurological symptoms (headaches, fainting, convulsions, or limb weakness).〔 Common sites of spread include the brain, bone, adrenal glands, opposite lung, liver, pericardium, and kidneys.〔 About 10% of people with lung cancer do not have symptoms at diagnosis; these cancers are incidentally found on routine chest radiography.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「lung cancer」の詳細全文を読む スポンサード リンク
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