Lung cancer
Lung cancer is a disease in which the cells of the lung tissues grow uncontrollably and form tumors. There are two kinds of lung cancers, primary and secondary. Primary lung cancer starts in the lung itself. Primary lung cancer isdivided into small cell lung cancer and non-small cell lung cancer, dependingon how the cells look under the microscope. Secondary lung cancer is cancerthat starts somewhere else in the body (for example, the breast or colon) andspreads to the lungs.
Small cell cancer was formerly called oat cell cancer, because the cells resemble oats in their shape. About a fourth of all lung cancers are small cell cancers. It is a very aggressive cancer and spreads to other organs within a short time. It is generally found in people who are heavy smokers. Non-small cell cancers account for the remaining 75% of lung cancers.
Tobacco smoking is the leading cause of lung cancer. Exposure to asbestos fibers, either at home or in the workplace, is also considered a risk factor for lung cancer. Besides asbestos, mining industry workers who are exposed to coal products or radioactive substances such as uranium, and workers exposed to chemicals such as arsenic, vinyl chloride, mustard gas, and other carcinogens also have a higher than average risk of contracting lung cancer. High levels of a radioactive gas (radon) that cannot be seen or smelled also pose a risk for lung cancer.
Inflammation and scar tissue produced in the lung due to certain diseases such as tuberculosis; and certain types of pneumonia may increase the risk of developing lung cancer. Although the exact cause of lung cancer is not known, people with a family history of lung cancer appear to have a slightly higher risk of contracting the disease.
The early symptoms of lung cancer are:
- A cough that does not go away
- Chest pain
- Shortness of breath
- Persistent hoarseness
- Swelling of the neck and face
- Significant weight loss that isnot due to dieting or vigorous exercise; fatigue and loss of appetite
- Bloody or brown-colored spit or phlegm (sputum)
- Unexplained fever
- Recurrent lung infections, such as bronchitis or pneumonia.
These symptoms may be caused by diseases other than lung cancer. It is vital,however, to consult a doctor to rule out the possibility that they are the first symptoms of lung cancer.
If the patient's doctor suspects lung cancer, he or she will take a detailedmedical history to check all the symptoms and assess the risk factors. This will be followed by a complete physical examination. If the doctor has reasonto suspect lung cancer--particularly if the patient has a history of heavy smoking or occupational exposure to substances that are known to irritate the lungs-- he or she may order a chest x ray to see if there are any masses in the lungs. Special imaging techniques, such as CT scans or MRIs, may provide more precise information about the size, shape, and location of any tumors.
Sputum analysis involves microscopic examination of the cells that are eithercoughed up from the lungs, or are collected through a special instrument called a bronchoscope. Sputum analyses can diagnose at least 30% of lung cancers. Lung biopsy is the most definitive diagnostic tool for cancer. After obtaining samples of the lung tissue or a sample of tissue from the tumor, it is sent to the laboratory. A pathologist examines the tumor samples to identify the cancer's type and stage.
Treatment for lung cancer depends on the type of cancer, its location, and its stage. The most commonly used modes of treatment are surgery, radiation therapy, and chemotherapy.
Surgery is not usually an option for small cell lung cancers, because they have usually spread beyond the lung by the time they are diagnosed. Because non-small cell lung cancers are less aggressive, however, surgery can be used totreat them. Surgery may be the primary method of treatment, or radiation therapy and/or chemotherapy may be used to shrink the tumor before surgery is attempted.
Radiotherapy involves the use of high-energy rays to kill cancer cells. It isused either by itself or in combination with surgery or chemotherapy. The amount of radiation used depends on the size and the location of the tumor. Radiation therapy may produce some side effects which may disappear either during the course of the treatment or after the treatment is over. The side effects should be discussed with the doctor.
Chemotherapy uses anti-cancer medications that are either given intravenouslyor taken by mouth. These drugs enter the bloodstream and travel to all partsof the body, killing cancer cells that have spread to different organs. Chemotherapy is used as the primary treatment for cancers that have spread beyondthe lung and cannot be removed by surgery. It can also be used in addition to surgery or radiation therapy.
If the lung cancer is detected before it has had a chance to spread to otherorgans, and if it is treated appropriately, at least 49% of patients can survive five years or longer after the initial diagnosis. Only 15% of lung cancers, however, are found at this early stage. Due to improvements in surgical technique and the development of new approaches to treatment, the one-year survival rate for lung cancer has improved considerably.
The best way to prevent lung cancer is not to smoke or to quit smoking if onehas already started. Secondhand smoke from other people's tobacco should also be avoided. Appropriate precautions should be taken when working with cancer-causing substances (carcinogens). Eating well-balanced meals, testing houses for the presence of radon gas, and removing asbestos from buildings are also useful preventive strategies.
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