Lung cancer x ray

Definition

Lung cancer is a disease in which the cells of the lung tissues grow uncontrollably and form tumors. It is the leading cause of death from cancer among both men and women in the United States. The American Cancer Society estimates that in 1998, at least 172,000 new cases of lung cancer will be diagnosed, and that lung cancer will account for 28% of all cancer deaths-- approximately 160,000 people.

Description

Types of lung cancer

There are two kinds of lung cancers, primary and secondary. Primary lung cancer starts in the lung itself. Primary lung cancer is divided into small cell lung cancer and non-small cell lung cancer, depending on how the cells look under the microscope. Secondary lung cancer is cancer that starts somewhere else in the body (for example, the breast or colon) and spreads 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. This type 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. They can be further subdivided into three categories.

Incidence of lung cancer

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.

Causes & symptoms

Causes

Tobacco smoking is the leading cause of lung cancer. Ninety percent of lung cancers can be prevented by giving up tobacco. Smoking marijuana cigarettes is considered yet another risk factor for cancer of the lung. These cigarettes have a higher tar content than tobacco cigarettes. In addition, they are inhaled very deeply-- as a result, the smoke is held in the lungs for a longer time.

Exposure to asbestos fibers, either at home or in the workplace, is also considered a risk factor for lung cancer. Studies show that compared to the general population, asbestos workers are seven times more likely to die from lung cancer. Asbestos workers who smoke increase their risk of getting lung cancer by 50-100 times. 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 pose a risk for lung cancer. This gas is produced by the breakdown of uranium, and does not present any problem outdoors. In the basements of some houses that are built over soil containing natural uranium deposits, however, radon may accumulate to dangerous levels. Having one's house inspected for the presence of radon gas when buying or renting is a good idea. Other forms of environmental pollution (e.g., auto exhaust fumes) may also slightly increase the risk of lung cancer.

Chronic lung inflammation and scarring

Inflammation and scar tissue are sometimes produced in the lung by diseases such as silicosis and berylliosis, which are caused by inhalation of certain minerals; tuberculosis; and certain types of pneumonia. This scarring 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.

Symptoms

Because lung cancers tend to spread very early, only 15% are detected in their early stages. The chances of early detection, however, can be improved by seeking medical care at once if any of the following symptoms appear:

• A cough that does not go away
• Chest pain
• Shortness of breath
• Persistent hoarseness
• Swelling of the neck and face
• Significant weight loss that is not 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 lung cancer has spread to other organs, the patient may have other symptoms such as headaches, bone fractures, pain, bleeding, or blood clots. Early detection and treatment can increase the chances of a cure for some patients; for others, it can at least prolong life.

Diagnosis

Physical examination and initial tests

If the patient's doctor suspects lung cancer, he or she will take a detailed medical history to check all the symptoms and assess the risk factors. The history-taking will be followed by a complete physical examination. The doctor will examine the patient's throat to rule out other possible causes of hoarseness or coughing, and listen to the patient's breathing and the sounds made when the patient's chest and upper back are tapped (percussed). The physical examination, however, is not conclusive.

If the doctor has reason to 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

Sputum analysis involves microscopic examination of the cells that are either coughed up from the lungs, or are collected through a special instrument called a bronchoscope. Sputum analyses can diagnose at least 30% of lung cancers, some of which do not show up even on chest x rays. In addition, the test can help detect cancer in its very early stages, before it spreads to other regions. The sputum test does not, however, provide any information about the location of the tumor and must be followed by other tests.