"This fact calls for effective smoking cessation programs that are likely to have major preventive effects even for smokers aged 60 years and older," German researchers write in Archives of Internal Medicine.

Their report, which summarizes the findings of 17 earlier studies, is the first to review the link between smoking and death in seniors in particular.

"Even older people who smoked for a lifetime without negative health consequences should be encouraged and supported to quit smoking," say the researchers, led by Dr. Hermann Brenner of the German Cancer Research Center in Heidelberg.

They found that smokers 60 years and older were 83 percent more likely to die at any given age compared with people who never smoked. While the link was weaker in the oldest people, it remained considerable even in those aged 80 and over.

Smoking researcher Dr. Prabhat Jha from St. Michael's Hospital in Toronto pointed to a British study, for instance, that followed doctors for half a century and found 59 percent of non-smokers were alive at age 80 compared to 26 percent of smokers.

In a commentary accompanying the German analysis, Dr. Tai Hing Lam of the University of Hong Kong said the findings show one in two elderly smokers will be killed by tobacco.

"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."

The studies in the current review lasted anywhere from three to 50 years and had anywhere between several hundred and more than 877,000 participants. All are based on observations of differences between current, former and never-smokers over time, which means there is no certainty that tobacco, itself, is responsible for the difference in death rates.

But the German researchers believe that's plausible because the chemicals in tobacco are known to cause cell damage and people who smoke more have shorter lives than those who smoke less.

Jha, who heads the Center for Global Health Research at St. Michael's, said the new report might overestimate the hazards of being a former smoker and underestimate the benefits of quitting.

That's because former smokers involved in the studies might have quit due to illness, thereby increasing their chances of early death, Jha told Reuters Health by email.

"Quitting works at any age," he said, "but is especially effective if people quit before disease."

According to the British study of doctors, he said, those who quit before age 40 had nearly the same death rates as those who never smoked.

SOURCE: bit.ly/LvmYaB Archives of Internal Medicine, online June 11, 2012.

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