LUNG CANCER
Lung Cancer is the type of cancer that forms in tissues of the lung, usually in the cells lining air passages. The two main types of lung cancer are small cell lung cancer and non-small cell lung cancer. These types of long cancer are diagnosed based on how the cells look under a microscope.
- Small cell lung cancer: About 13 percent of lung cancers are small cell lung cancers. This type of lung cancer tends to spread quickly.
- Non-small cell lung cancer: Most lung cancers (about 87 percent) are non-small cell lung cancers. This type of lung cancer spreads more slowly than small cell lung cancer.
The Lungs
Your lungs are a pair of large organs in your chest. They are part of your respiratory system. Air enters your body through your nose or mouth. It passes through your windpipe (trachea) and through each bronchus, and goes into your lungs. When you breathe in, your lungs expand with air. This is how your body gets oxygen.
When you breathe out, air goes out of your lungs. This is how your body gets rid of carbon dioxide. Your right lung has three parts (lobes). Your left lung is smaller and has two lobes.
A thin tissue (the pleura) covers the lungs and lines the inside of the chest. Between the two layers of the pleura is a very small amount of fluid (pleural fluid). Normally, this fluid does not build up.
Risk Factors
Doctors cannot always explain why one person develops lung cancer and another does not. However, we do know that a person with certain risk factors may be more likely than others to develop lung cancer. A risk factor is something that may increase the chance of developing a disease.
Known risk factors for lung cancer:
- Tobacco smoke: Tobacco smoke causes most cases of lung cancer. It's by far the most important risk factor for lung cancer. Harmful substances in smoke damage lung cells. That's why smoking cigarettes, pipes, or cigars can cause lung cancer and why secondhand smoke can cause lung cancer in nonsmokers. The more a person is exposed to smoke, the greater the risk of lung cancer. For more information, see the NCI fact sheets Quitting Smoking and Secondhand Smoke.
- Radon: Radon is a radioactive gas that you cannot see, smell, or taste. It forms in soil and rocks. People who work in mines may be exposed to radon. In some parts of the country, radon is found in houses. Radon damages lung cells, and people exposed to radon are at increased risk of lung cancer. The risk of lung cancer from radon is even higher for smokers. For more information, see the NCI fact sheet Radon and Cancer.
- Asbestos and other substances: People who have certain jobs (such as those who work in the construction and chemical industries) have an increased risk of lung cancer. Exposure to asbestos, arsenic, chromium, nickel, soot, tar, and other substances can cause lung cancer. The risk is highest for those with years of exposure. The risk of lung cancer from these substances is even higher for smokers.
- Air pollution: Air pollution may slightly increase the risk of lung cancer. The risk from air pollution is higher for smokers.
- Family history of lung cancer: People with a father, mother, brother, or sister who had lung cancer may be at slightly increased risk of the disease, even if they don't smoke.
- Personal history of lung cancer: People who have had lung cancer are at increased risk of developing a second lung tumor.
- Age over 65: Most people are older than 65 years when diagnosed with lung cancer.
Symptoms of Liver Cancer
Early lung cancer often does not cause symptoms. But as the cancer grows, common symptoms may include:
- a cough that gets worse or does not go away
- breathing trouble, such as shortness of breath
- constant chest pain
- coughing up blood
- a hoarse voice
- frequent lung infections, such as pneumonia
- feeling very tired all the time
- weight loss with no known cause
Finding Lung Cancer Cells
The only sure way to know if lung cancer is present is for a pathologist to check samples of cells or tissue. The pathologist studies the sample under a microscope and performs other tests. There are many ways to collect samples.
Your doctor may order one or more of the following tests to collect samples:
- Sputum cytology: Thick fluid (sputum) is coughed up from the lungs. The lab checks samples of sputum for cancer cells.
- Thoracentesis: The doctor uses a long needle to remove fluid (pleural fluid) from the chest. The lab checks the fluid for cancer cells.
- Bronchoscopy: The doctor inserts a thin, lighted tube (a bronchoscope) through the nose or mouth into the lung. This allows an exam of the lungs and the air passages that lead to them. The doctor may take a sample of cells with a needle, brush, or other tool. The doctor also may wash the area with water to collect cells in the water.
- Fine-needle aspiration: The doctor uses a thin needle to remove tissue or fluid from the lung or lymph node. Sometimes the doctor uses a CT scan or other imaging method to guide the needle to a lung tumor or lymph node.
- Thoracoscopy: The surgeon makes several small incisions in your chest and back. The surgeon looks at the lungs and nearby tissues with a thin, lighted tube. If an abnormal area is seen, a biopsy to check for cancer cells may be needed.
- Thoracotomy: The surgeon opens the chest with a long incision. Lymph nodes and other tissue may be removed.
- Mediastinoscopy: The surgeon makes an incision at the top of the breastbone. A thin, lighted tube is used to see inside the chest. The surgeon may take tissue and lymph node samples.
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