"Deaths from lung cancer are still falling, but the rate of decrease is slowing and that is very worrisome," says lead author Ahmedin Jemal, PhD, DVM, a fellow in the biostatistics branch of the National Cancer Institute?s division of cancer epidemiology and genetics. "We''re seeing the result of increasing rates of smoking initiation when today''s baby boomers were teenagers."

Earlier studies had shown continuing decreases in deaths from lung cancer among Americans born before 1950. The steady decline in lung cancer incidence and death matches long-term efforts by the American Cancer Society (ACS) and other groups to convince smokers to quit. Jemal looked at younger smokers, comparing lung cancer cases and deaths from 1970 to 1997 among different age groups born after 1950.

"This was a complete surprise," he says. "Everybody thought there was a very strong, very steady decline in lung cancer rates for the entire population. This trend tells us that early intervention, convincing children and teenagers not to start smoking or to stop if they''ve started, is the best way to cut overall mortality for lung cancer."

Cigarette smoking is the primary risk factor for lung cancer, which will kill about 157,000 people in the United States this year, according to ACS estimates. But the incidence of lung cancer and death rates vary with age. Among men, lung cancer rates are highest for those born between 1925 and 1930. Among women, lung cancer rates peak for those born between 1935 and 1940. The difference reflects the trends in cigarette smoking among men and women, with men traditionally starting to smoke earlier and smoking longer than women.

The U.S. smoking rate has been dropping since about 1960, Jemal says, and overall lung cancer mortality has been falling since 1990. But smoking trends among teenagers and young adults has not shown the same general decline. Instead, there have been peaks and valleys corresponding to social changes and tobacco advertising targets, he says.

This is a disturbing trend, says Alan Henderson, DrPH, professor of health sciences at California State University, Long Beach, and past president of the ACS? California division. "When there is an increase in tobacco use among young people, there will be an increase in lung cancer. We now know that we can expect an increase in lung cancer down the road as a direct result of teen smoking increases," he says.

Henderson says the study emphasizes the need to strengthen tobacco control programs. Tobacco companies may have shifted their advertising efforts to 18- to 24-year-olds, but starting to smoke at any age directly increases the risk of lung cancer in later years, he says.

"This report only reinforces our public health efforts at tobacco surveillance and control," Henderson says. "The target has to be young people, getting them to quit or not to start in the first place."