What is lung cancer?
Lung cancer is the cancer that originates in the tissues of the lungs. Lung cancer occurs when cells in the lung start to grow rapidly in an uncontrolled manner. Lung cancer can start anywhere in the lungs and affect any part of the respiratory system. It is the leading cause of cancer deaths in both men and women. Most lung cancers start in the lining of the bronchi. That is why another term for lung cancer is bronchogenic cancer. Lung cancer can also form in glands below the lining of the
bronchi, frequently in the periphery of the lungs. Lung cancers are thought to develop over a period of many years. First, there may be areas of precancerous changes in the lung. These changes do not form a mass or tumor. They cannot be seen on an x-ray and they do not cause symptoms. But, these precancerous changes can be found by analyzing cells in the lining of the airways of smoke-damaged lungs. Under normal circumstances, lung cells reproduce in an orderly fashion to maintain tissue health and to repair injuries. However, when growth control is lost and cells divide too much and too fast, a cellular mass - or tumor - is formed. If the tumor is confined to a few cell layers (for example, surface cells) and it does not invade surrounding tissues or organs, it is considered benign. By contrast, if the tumor spreads to surrounding tissues or organs, it is considered malignant, or cancerous. If cancerous cells break away from the original tumor, travel, and grow within other body parts- such as the brain, bone, liver, adrenal glands, the opposite lung, or lymph nodes of the chest or collarbone (clavicle) regions - the process is known as metastasis.
Exposure to carcinogens, such as those present in tobacco smoke, immediately causes small changes to the tissue lining the bronchi of the lungs (the bronchial mucous membrane). This effect is cumulative, and over time with continued exposure more and more tissue gets damaged until a tumour develops. If the tumour grows inwards it may obstruct the air passageway, causing breathing difficulties. The lungs may then collapse and infections can develop, leading to lung abscess. The patient here would start to cough up blood-stained material. However, if the tumour grows outwards in to the lung it may not even be noticed by the patient before it starts to spread to other parts of the body. Common symptons include: coughing up blood or lung-material; a bad, chronic cough; wheezing; chest pains; weight loss or loss of appetite; and shortness of breath.
Lung cancer is the leading cause of cancer deaths in both women and men in the United States, Canada, and China. In several other countries, lung cancer is the number one cause of cancer deaths in men and the second or third cause among women. Only about 14% of all people who develop lung cancer survive for 5 years. Like other cancers, lung cancer occurs after repeated insults to the genetic material of the cell. By far the most common source of these insults is tobacco smoke, which is responsible for about 85% of U.S. lung cancer deaths (see smoking). The incidence of lung cancer in other countries follows their smoking patterns. Some other carcinogens known to cause lung cancer are found in the workplace. These include bischloromethyl ether and chloromethyl ether in chemical workers, arsenic in copper smelting, and asbestos in shipbuilders and other asbestos workers. Radon poses a risk to uranium and fluorspar miners and may pose a risk in some private residences as well. African Americans have a higher incidence of lung cancer than European Americans, even after adjusting for smoking.
Lung cancer is rare among young adults. It is usually found in people who are 50 years of age or older, the average age at diagnosis being 60. While the incidence of the disease is decreasing among white men, it is steadily rising among African-American men, and among both white and African-American women. This change is probably due to the increase in the number of smokers in these groups. In 1987, lung cancer replaced breast cancer as the number one cancer killer among women.
Lung cancers are classified according to the type of cell present in the tumor. The majority are referred to as non–small cell carcinomas. These include squamous cell or epidermoid carcinomas (the most common type worldwide), adenocarcinomas, and large cell carcinomas. Small cell carcinoma (which includes the subtypes oat cell and intermediate) comprises approximately 20% to 25% of lung cancers; it often has metastasized by the time it is detected. Lung cancer most commonly spreads to the brain, bone, liver, or bone marrow. Lung cancer that originates in the cells of the lungs is called primary lung cancer; however, cancer may also spread (metastasize) to the lung from other parts of the body. Metastatic cancers spread to the lungs most commonly from the breast, colon, prostate, kidney, thyroid gland, stomach, cervix, rectum, testis, bone, and skin (melanoma).
More information on lung cancer
What is lung cancer? - Lung cancer is a malignant tumour of the lungs. Lung cancer is the cancer that originates in the tissues of the lungs. Lung cancer is the leading cause of cancer deaths.
What types of lung cancer are there? - The lungs are made up of several kinds of cells that perform different functions. The type of lung cancer depends on which cell type is affected.
What is small cell lung cancer? - Small cell lung cancer is a type of lung cancer in which the cells look like oats. Small cell lung cancer is almost always caused by smoking.
What is non-small cell lung cancer? - Non-small cell lung cancers include squamous cell carcinoma, adenocarcinoma, large cell carcinoma, adenosquamous carcinoma, and undifferentiated carcinoma.
What causes lung cancer? - Cigarette smoking is the most significant cause of lung cancer. Asbestos exposure increases the risk of lung cancer. Lung diseases create a risk for lung cancer.
What're the risk factors for lung cancer? - Risk factors for lung cancer include tobacco smoking, marijuana, asbestos, radon, lung diseases, radiation therapy, work-related exposure to substances.
What're the signs and symptoms of lung cancer? - Lung cancer may cause a number of symptoms. The primary symptoms of lung cancer are cough, shortness of breath, hoarseness, blood in the sputum, and pain.
How is lung cancer diagnosed? - Diagnosis of lung cancer may be made by physical examination, chest X rays, bronchoscopy, or percutaneous needle biopsy. Lung biopsy is the most definitive diagnostic tool for cancer.
What're the lung cancer stages? - Lung cancer is staged according to its location, size, cell type, and spread. Knowing the stage of lung cancer helps the doctor set the treatment plan.
What're the treatments for lung cancer? - The treatment of lung cancer depends on the type and stage of the disease and includes surgery, radiation therapy, and chemotherapy.
What's the treatment for small cell lung cancer? - At limited stage treatments for small cell lung cancer include various combinations of chemotherapy, radiation.
What's the treatment for non-small cell lung cancer? - Surgery is the primary treatment for all non¨Csmall cell lung cancers. Radiation therapy may be administered.
Treatment for non-small cell lung cancer by stage - Stage III non-small cell lung cancer are treated with radiation and sometimes with surgery, chemotherapy, or combinations of each.
What's the prognosis of lung cancer survival rate? - The prognosis of lung cancer depends on the type of lung cancer, its stage, and the overall health of the patient.
How to prevent lung cancer? - Prevention of lung cancer includes quitting smoking and avoiding exposure to potentially cancer-causing substances in the work environment.
Asbestos lung cancer - The most serious hazard of exposure to asbestos is cancer. Lung cancer causes the largest number of deaths related to asbestos exposure.