(CBS News) A new report shows that quitting smoking might make you live longer - regardless of how old you are.
The study, which was published in the Archives of Internal Medicine on June 11, looked at results from17 studies conducted in seven countries. Even seniors lived longer if they were willing to part with their cigarettes.
According to the researchers, smoking is one of the 10 leading risk factors for death, and takes the lives of 12 percent of males and six percent of females of the world. If current rates continue, one billion deaths due to smoking are expected in the 21st century.
Researchers reviewed studies that ranged in duration from three to 50 years and looked at anywhere from 863 participants to more than 877,000 people. One study showed that 59 percent of non-smokers were alive at age 80, compared to 26 percent of smokers. Another study showed that those who had quit before the age of 40 had the same death rates as those who had never smoked.
The researchers also found that smokers who were 60 years and older were 83 percent more likely to die at any given age than those in the same age group who had never smoked. Some causes of death - such as cancers of the mouth, pharynx, and larynx - increased up to 10 times for current smokers in that age group. Those who quit smoking still had a higher risk of dying at any given age compared to those who never picked up the habit - 34 percent - but it was much lower than those who never quit.
However, for those willing to quit, mortality was comparable with never-smokers the longer they had stopped using cigarettes.
"These results strongly suggest that smoking cessation is effective for mortality reduction also at older age, a suggestion that should be corroborated by intervention studies, ideally with interventions specifically designed and developed for this target group," the researchers wrote.
A weaker, yet similar correlation was also found for those who were 80 and older.
The researchers suggested that even people who smoked their whole lives without negative consequences should be encouraged to quit. Because the retirement age has been pushed back due to the need to work longer, the individual and public health burden of smoking-related illness will increase unless strides are made to help people stop.
In a corresponding commentary published in the same journal issue, Dr. Tai Hing Lam, a professor of public health at The University of Hong Kong, reminded the community that tobacco kills one out of two users, and about half of the teenagers who keep smoking will die of of tobacco use - a quarter in middle age and a quarter are expected to die in old age. He pointed out that because some smokers, especially those in Asia, might not have used the products as long as in the United States or in the United Kingdom, they may benefit from cessation programs even more. Lam suggested that while brief, less than 20 minute clinical interventions by health care professionals might be practical, simply showing them the fact that one in two tobacco users will die from continued use may work.
"Most smokers grossly underestimate their own risks," he wrote. "Many older smokers misbelieve that they are too old to quit or too old to benefit from quitting. Because of reverse causality and from seeing deaths of old friends who had quit recently, some misbelieve that quitting could be harmful. A simple, direct, strong, and evidence-based warning is needed."