TUESDAY, June 22, 2004 (HealthDayNews) -- The dangers of smoking and the benefits of quitting are far greater than researchers previously thought, and it can take years for those dangers and benefits to manifest.
According to a prospective study on the dangers of smoking that date back half a century, cigarette smokers die an average of 10 years sooner than nonsmokers.
At least half, and possibly up to two-thirds, of people who smoke from youth are eventually killed by their habit, a quarter of them while in middle age (ages 35 to 69).
"There are risks in life, but you don't have many things that kill half of those that do them," Said Sir Richard Peto, professor of medical statistics and epidemiology at the University of Oxford, who announced the results at a press conference Tuesday in London.
The good news is that quitting has advantages. Stopping at age 50 cuts the risk of dying in half, while quitting at 30 almost eliminates the risk. These numbers echo the findings of Duke University researchers, who found that people who quit smoking before the age of 35 have a reasonable chance of living as long and as well as those who have never smoked.
"When you get bigger hazards, you get bigger benefits from stopping," Peto said. "The key emphasis for practical purposes is how big the risk is if you smoke, and how big the benefit when you stop. Smoking kills half. Stopping works."
The results of the longest study ever into the effects of smoking will appear in the June 26 issue of the British Medical Journal, 50 years to the day after the first landmark results from the same study, which confirmed the link between lung cancer and smoking, were reported.
In addition to Peto, Sir Richard Doll, who launched the study in 1951, was present at the news conference to announce the results. Doll, who was in his 30s when the study began, quit smoking at the age of 37 after the first study results were published and is now in his 90s. "He's alive and, as of an hour ago, really enjoying himself," said Peto, who himself quit smoking at the age of 23 after seven years of inhaling. "Stopping works unreasonably well, no matter when you stop."
Peto and Doll are among the lucky (or smart) ones. In the intervening 50 years, according to the study authors, tobacco has killed about 6 million people in the United Kingdom alone and 60 million across the developed world.
Cigarettes first appeared in the early part of the 20th century. "Britain got on smoking before anyone else did," Peto explained. "We followed this first generation through their whole life span, the better part of 100 years."
An initial questionnaire was sent to 34,439 male doctors in Britain born between 1900 and 1930. Additional questionnaires were sent in later years, most recently in 2001.
Earlier results from the study found that smokers died an average of eight years sooner than their nonsmoking counterparts. The latest results make that 10 years.
During the course of the study, about half of the cigarette smokers were killed by their habit. Those born around 1920, however, had even higher mortality, with about two-thirds dying from smoking-related illnesses. The study authors believe that this is because these men were drafted into the British army at the beginning of World War II, which provided cheap cigarettes to conscripts.
Quitting smoking at age 60 adds about three years to one's life. Stopping at 50, 40, or 30 adds six, nine and 10 years respectively.
"The health issue after you quit is still remarkable even for those who quit later in life," said Dr. Elliot Wineburg, a smoking cessation expert who is clinical professor of psychiatry at Mount Sinai School of Medicine in New York City. Wineburg cites additional statistics showing that within one year of quitting, the excess risk of coronary heart disease is cut in half. Within 20 minutes, blood pressure drops to normal.
"I think we've sometimes emphasized whether kids start almost to the detriment of whether adults stop," Peto said. "By the time you're 30, you've got some understanding of life and death, and when you're 40 you have substantial understanding of life and death; it's for people old enough to know that death is real. If you stop then, you'll probably get away with it. There's some risk left over, but it's really small in comparison with other things in life."
For resources on how to quit smoking, visit the U.S. Centers for Disease Control and Prevention.