Is cigarette smoke the only cause of lung cancer?
Radon and asbestos are causes, too. Radon is an invisible, odorless, and radioactive gas that occurs naturally in soil and rocks. Asbestos has been used for fireproofing, electrical insulation, building materials, brake linings, and chemical filters. But cigarette smoking is the number one cause of lung cancer. Before cigarette smoking became popular in the early part of the 20th century, doctors rarely saw patients with lung cancer. Nearly 90 percent of people with lung cancer developed it because they smoked cigarettes. The good news is that smoking is not as popular as it used to be. In 1965 about 42 percent of all adults smoked, but by 1997, only 25 percent did. Also, there has been a sharp drop in lung cancer deaths among men, mainly because fewer men are smoking. Lung cancer is the leading cause of cancer death in men and women in the United States. It occurs most often between the ages of 55 and 65. Common symptoms of lung cancer include: a persistent cough that worsens, constan
