Reviewed by Dr. Clement J. Cheng
Lung cancer is the leading cause of cancer death in men and women. In the year 2000, approximately 156,900 people will die of lung cancer—approximately 89,300 men and 67,600 women.
In the same year, 164,100 new cases of lung cancer will be diagnosed. Only 1 percent of lung cancer patients are under age 30; only 10 percent are older than 70. The average age of people diagnosed with lung cancer is 60.
If discovered early, the five-year survival rate for a lung cancer patient is 42 percent. However, it is rarely found before it has spread to the lymph nodes or other organs. The five-year survival rate for all stages of lung cancer was 14 percent in 1995.
Lung tumors usually start in the walls of the bronchi—the branching, tubular airways of the lungs. It usually takes many years to develop, but once it occurs it can spread to other areas of the body without detection.
Most people with early lung cancer do not exhibit any symptoms, so their cancer is rarely diagnosed at an early stage. Any of the following symptoms should be reported to a doctor:
- Chronic, hacking cough, sometimes accompanied by bloody sputum
- Recurrent respiratory infections
- Shortness of breath
- Persistent chest pain
- Hoarseness
- Swelling in the neck and face
- Fatigue
- Weight loss
- Severe headaches
- Intermittent fever
- Loss of appetite
When the lung cancer has spread to other organs, the following symptoms may appear:
- Bone pain or weakness in the shoulder, hand, or arm
- Jaundice on the skin and around the eyes
- Masses near the surface of the body, due to the cancer’s spread to the lymph nodes in the neck
Two types of lung cancer exist: small-cell lung cancer and nonsmall-cell lung cancer.
Small-cell lung cancer accounts for approximately 20 percent of all lung cancers. Though the cancer cells are small, they multiply rapidly and form large tumors. It usually spreads to the lymph node or other organs before diagnosis. In most cases, smoking is the cause of small-cell lung cancer. Another name for this cancer is oat cell cancer because it looks like oatmeal under a microscope.
Non-small cell lung cancer is the most common lung cancer. Three sub-types exist: squamous cell carcinoma, adenocarcinoma, and large-cell carcinoma.
Squamous cell carcinoma usually starts in the central bronchi, which are the largest branches of the bronchial tree. Men and smokers are most susceptible to this type of lung cancer. It is easier to detect early because its cells show up well in sputum samples. Because it spreads slowly, it is the most curable.
Adenocarcinoma is most common in women and nonsmokers and usually originates on the outer edge of the lungs, in the small bronchi. It most often spreads to spaces between the lungs and chest wall; this location makes detection difficult.
Large-cell carcinomas tend to originate on the outer edges of the lungs. They are marked by large, abnormal-looking cell and are the least common of the non-small cell lung cancers.
People’s genes influence their susceptibility to lung cancer. Lung cancer tends to run in families, so a certain predisposition may be inherited. Also, some people are more susceptible to carcinogens like those found in tobacco smoke.
Cigarette smoking has been identified as the leading cause of lung cancer; at least four out of five lung cancer cases are associated with cigarette smoking. Anyone who smokes one pack of cigarettes a day is 20 times more likely than a nonsmoker to develop lung cancer. And the risk increases as the number of cigarettes smoked per day increases.
Smokers who quit the habit significantly reduce their risk of developing lung cancer, although they will always be slightly more at risk than nonsmokers. Cigar and pipe smokers are almost as likely to develop lung cancer as cigarette smokers.
Secondhand tobacco smoke can cause lung cancer in nonsmokers. Nonsmokers who live or work with smokers are at a higher risk for developing the disease.
The best way to prevent lung cancer is not to smoke or be around secondhand tobacco smoke. People who do smoke should quit.
Workers who work daily with silica, asbestos, coal dust, or radon are more likely than the average person to develop lung cancer as well. However, some people who have never smoked or worked with asbestos still develop lung cancer.
Several imaging tests may be used to diagnose lung cancer: X-rays, MRI, CT scan, and PET scan.
