The lungs, a pair of sponge-like, cone-shaped organs, are part of the respiratory system. The right lung has three sections called lobes; it is a little larger than the left lung which has two lobes. Cancers that begin in the lungs are divided into two major types: nonsmall cell lung cancer and small cell lung cancer, depending on how the cells look under a microscope. Each type of lung cancer grows and spreads in different ways and is treated differently.
cell lung cancer is more common than small cell lung cancer, and it generally grows and spreads more slowly. There are three main types of nonsmall cell lung cancer. They are named for the type of cells in which the cancer develops: squamous cell carcinoma (also called epidermoid carcinoma), adenocarcinoma, and large cell carcinoma.
Small cell lung cancer sometimes called oat cell cancer, is less common than nonsmall cell lung cancer. This type of lung cancer grows more quickly and is more likely to spread to other organs in the body.
Possible Causes: Researchers have discovered several causes of lung cancer, and most are related to the use of tobacco:
Cigarettes. Smoking cigarettes causes lung cancer. Harmful carcinogens in tobacco damage cells in the lungs. Over time, the damaged cells may become cancerous. The likelihood that a smoker will develop lung cancer is affected by the age at which smoking began, how long the person has smoked, the number of cigarettes smoked per day, and how deeply the smoker inhales.
Cigars and Pipes. Cigar and pipe smokers have a higher risk of lung cancer than nonsmokers. Even cigar and pipe smokers who do not inhale are at increased risk for lung, mouth, and other types of cancer.
Environmental Tobacco Smoke. The chance of developing lung cancer is increased by exposure to environmental tobacco smoke (also known as secondhand smoke) or the smoke in the air when someone else smokes.
Radon. Radon is an invisible, odorless, and tasteless radioactive gas that occurs naturally in soil and rocks. People who work in mines may be exposed to radon and in some parts of the country radon is found in houses. A kit available at most hardware stores allows homeowners to measure radon in their homes.
Asbestos. Asbestos is the name of a group of minerals that occur naturally as fibers and are used in certain industries. Asbestos fibers tend to break easily into particles that can float in the air and stick to clothes. When the particles are inhaled, they can lodge in the lungs, damaging cells and increasing the risk for lung cancer. This exposure has been observed in such industries as shipbuilding, asbestos mining and manufacturing, insulation work, and brake repair.
Pollution. Researchers have found a link between lung cancer and exposure to certain air pollutants, such as by-products of the combustion of diesel and other fossil fuels. More research is being done to clarify things.
Lung Diseases. Certain lung diseases, such as tuberculosis (TB), increase a person's chance of developing lung cancer. The cancer tends to develop in areas of the lung that are scarred from TB.
Medical History. A person who has had lung cancer once is more likely to develop a second lung cancer compared with a person who has never had lung cancer. Quitting smoking after the lung cancer is diagnosed may prevent the development of a second lung cancer.
The best known way to prevent lung cancer is to quit or never start smoking.
Symptoms: Preliminary testing to detect a lung condition can include a review of a person's medical history, smoking history and any occupational hazards. A chest x-ray and other tests may also be given. If lung cancer is suspected, sputum cytology (a microscopic examination of cells obtained from a deep-cough sample of mucus in the lungs) is a simple test that may be useful in detecting lung cancer. To confirm the presence of lung cancer, the doctor must examine tissue from the lung. The removal of a small sample of tissue for examination under a microscope by a pathologist is called a biopsy, and can detect cancer. A number of procedures may be used to obtain the tissue:
Bronchoscopy. The doctor puts a bronchoscope (a thin lighted tube) into the mouth or nose and down through the windpipe to look into the breathing passages. Through this tube, the doctor can collect cells or small samples of tissue.
Needle aspiration. A needle is inserted through the chest into the tumor to remove a sample of tissue.
Thoracentesis. Using a needle, the doctor removes a sample of the fluid that surrounds the lungs to check for cancer cells.
Thoracotomy. Surgery to open the chest is sometimes needed to diagnose lung cancer. This procedure is a major operation performed in a hospital.
Types of Lung Cancer
Small Cell Lung Cancer
is less common than non-small cell lung cancer. Small Cell Lung Cancer accounts for fifteen percent of all diagnoses, and is most prevalent among smokers. Small Cell Lung Cancer is also called oat cell cancer, because malignant cells are oat-shaped. Small Cell Lung Cancer is aggressive, and spreads quickly. In approximately seventy percent of cases the cancer has spread to other organs by the time the disease is diagnosis. Once metastasized, a Small Cell Lung Cancer patient is not a candidate for surgery but does respond to chemotherapy.
Limited Small Cell Lung Cancer
About one third of patients with SCLC have limited disease at initial diagnosis. This stage is highly responsive to a combination of systemic chemotherapy and radiation. Substantial shrinkage of tumor occurs in as many as 80% to 90% of patients with this treatment. Complete clinical remission can be achieved in 50% to 60% of all patients with this stage of disease. Recent trials of chemotherapy and radiation show median survival times of 15 to 18 months, 2-year survival rates of 30% to 40%, and 5-year survival rates of 10% to 15%.
Extensive Small Cell Lung Cancer
In the two thirds of patients with SCLC who have extensive disease at initial diagnosis, the response rate to systemic chemotherapy is 60% to 80%, median survival time is 9 to 10 months, and the 2-year survival rate is less than 10%. Five-year survival with extensive disease is rarely reported. Complete clinical remission is achieved in only 20% to 30%. The chemotherapeutic agents given for extensive disease are identical to those used for limited disease.
Mesothelioma - Cancer of the Lung Lining
Mesothelioma symptoms in patients with cancer of the pleura. Mesothelioma symptoms are often vague. They may include a gradual increase in shortness of breath. Patients may develop local spread of the cancer or metastatic disease. A collection of fluid around the lung may develop called a pleural effusion. Cough, sputum production, and wheezing are not uncommon, and are often related to the underlying lung disease and smoking rather than the cancer.
The most common symptoms of pleural mesothelioma are difficulty in breathing, chest pain, or both. Occasionally, a patient may not have symptoms at diagnosis. Other less common symptoms include weight loss, fever, night sweats, cough, and a general feeling of not being well. Symptoms of peritoneal mesothelioma may include swelling, pain due to accumulation of fluid in the abdomen cavity, weight loss, and a mass in the abdomen. Other symptoms of peritoneal mesothelioma may include bowel obstruction, blood clotting abnormalities, anemia (a lowered red blood cell count), and fever.
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