Chapter 5 Lung Cancer Whos At Risk: Cancer

Content provided by the Faculty of the Harvard Medical School

Chapter 5: Lung cancer - Who's at risk

Lung cancer, the nation's leading cancer killer, is also the easiest to prevent. The most common cause of lung cancer is tobacco smoke, which contains 4,000 chemicals, including more than 40 known carcinogens capable of damaging the genetic material in cells and initiating the development of cancer. Lung cancer is the leading cause of cancer deaths in both men and women, resulting in more deaths than breast cancer and prostate cancer combined.

Although the incidence of lung cancer is decreasing in men, for women it continues to grow. And because there are usually no symptoms in its early stages, lung cancer often is not detected until it has already spread to lymph nodes and other organs, at which point it becomes far less treatable.

People who smoke tobacco are at the greatest risk for developing lung cancer. The longer a person has smoked - and the more cigarettes he or she has smoked - the greater the risk. Research suggests that cigar or pipe smoking could be equally hazardous. Scientists who conducted a series of studies on the health effects of cigar and pipe smoking concluded that these forms of smoking might increase cancer risk just as much as cigarettes do.

Nonsmokers who breathe the smoke of others are also at increased risk of lung cancer because secondhand smoke contains cancer-causing chemicals. Breathing secondhand smoke also leads to other health problems -such as coughing, respiratory infections such as pneumonia and bronchitis, and an increased number and severity of asthma attacks.

Exposure to asbestos is another important risk factor, especially for smokers. Asbestos workers have about seven times more risk of developing lung cancer than do people in general, and asbestos workers who also smoke face a risk 50 to 90 times greater.

Although lung cancers rarely result from inherited genes, some people may have an inherited predisposition that makes them more vulnerable to cancer-causing chemicals. People who have other lung diseases (tuberculosis, silicosis, or berylliosis) or have had lung cancer in the past are also at greater risk for developing lung cancer. Air pollution may also slightly increase your risk of lung cancer, but none of these factors has anywhere near the deadly impact that smoking does.

Risk factors for lung cancer cigarette smoking breathing secondhand smoke previous lung disease increasing age exposure to toxins with a known link to lung cancer

How Lung Cancer Forms The most common form of lung cancer, known as squamous cell carcinoma or epidermoid cancer, starts in the lining or lumen of the secondary airways, known as the bronchi. The lumen's epithelial cells are acted upon by carcinogens that enter the lung, such as tobacco smoke or asbestos. Mutated cells begin to proliferate, penetrating surrounding tissues and gradually interfering with lung function and possibly spreading to other parts of the body.

Last updated:	May 01, 2008