An estimated 146, 000 Americans died of lung cancer in 1992, and 90 percent of these deaths were caused by cigarette smoking. Smoking is responsible for about 30 percent of all cancer deaths annually in the United States more than 155, 000 each year. If smoking-related cancers could be eliminated from our society, we would see a significant decline in the annual cancer death rate instead of small but steady increases. Since 1964, the year of the Surgeon General's first report on the health risks of cigarette smoking, strong evidence of the association between smoking and cancer has accumulated. Countless studies have proved that smoking causes lung cancer, and we now know that it substantially increases a person's risk of developing cancer of the larynx, pharynx, oral cavity, esophagus, bladder, kidney, and pancreas.

Additional studies suggest a strong association between smoking and cancer ofthe cervix. The risk of developing lung and other smoking-associated cancers is related to total lifetime exposure to cigarette smoke, as measured by the number of cigarettes smoked each day, the age at which smoking began, and the number of years a person has smoked. Likewise, the risk of developing other smoking- related diseases, including chronic lung diseases and coronary heart disease, also increases with the amount of smoking a person has done. The health risks associated with cigarette smoke are not limited to smokers: exposure to environmental tobacco smoke (ETS) significantly increases a nonsmoker " risk of developing lung cancer. (ETS is the smoke that nonsmokers are exposed to when they share air space with someone who is smoking.

) The U. S. Environmental Protection Agency (EPA) released a risk assessment report in December 1992, in which ETS was classified as a Group A (known human) carcinogen a category reserved for only the most dangerous cancer-causing agents. The EPA report estimates that ETS is responsible for several thousand lung cancers in nonsmokers each year and, perhaps equally important, links ETS exposure with severe respiratory problems in infants and young children.

The good news is that a smoker's risk of developing lung and other cancers can be reduced by quitting. The risk begins to decrease immediately after quitting and continues to decline gradually each year. Another benefit is that the risk of developing other cancers and chronic diseases associated with smoking is also reduced. The risk of coronary heart disease, for example, declines substantially within only a few short years following cessation.

Women who quit smoking during the first trimester (3 months) of pregnancy substantially reduce the risk of such adverse pregnancy outcomes as low birth weight or stillbirth.