Smokers who quit by around age 40 can stave off an early death, according to a landmark study that fills key gaps in knowledge of smoking-related health ills.
While smokers who never stop lose about a decade of life expectancy, those who quit between ages 35 and 44 gained back nine of those years, the study found.
Moreover, the benefits of dropping the habit extend deep into middle age. Smokers who quit between ages 45 and 54 gained back six otherwise lost years, and those who quit between ages 55 and 64 gained four years.
Quitting young, before age 35, erased the entire decade of lost life expectancy.
The message: It's never too late to quit, even for heavy smokers with decades of puffing behind them.
But younger smokers should not be lulled into thinking they can smoke until 40 and then stop without consequences, said Prabhat Jha, an epidemiologist at the Center for Global Health Research in Toronto. Jha led the new study, published online Wednesday in the New England Journal of Medicine.
That's because the risks of lung cancer and other respiratory diseases linger for years after a smoker stubbs his last butt.
While the study delivered some good news for quitters, it also hammered home the message that continuing to smoke carries grave risks.
Current smokers in the study died early at a rate triple that of people who never smoked. And few smokers reached age 80. Just 38 percent of female smokers and 26 percent of male smokers hit that milestone, while 70 percent of women who never smoked and 61 percent of men who never smoked did.
The study linked surveys of 217,000 adults collected for the federal National Health Interview Survey between 1997 and 2004 to cause-of-death records in the National Death Index.
A second report, also published in the New England Journal of Medicine, showed that smoking-related deaths among women have soared in recent decades. For the first time since research on smoking and health began in the 1950s, the rate of smoking-related deaths is now nearly equal between male and female smokers.
Women took to cigarettes in large numbers only after World War II, lagging behind men by about 20 years. The consequences of that shift are just now reaching women in their mid 50s and older. Meanwhile, lung cancer risk in male smokers leveled off in the 1980s.
"As the Mad Men generation has matured, the risks in women who smoke continue to increase," said Michael Thun of the American Cancer Society, lead author of the second report, which drew on that group's Cancer Prevention Study. That study tracked 1.2 million men and women through 2010.
"We used to think women were at less risk of illness from smoking," said Steven Schroeder, a smoking and health expert at the University of California, San Francisco, who was not involved in either study. "That doesn't seem to be true now. My guess is that early women smokers didn't smoke as much as men because there was some stigma to it. Now they're smoking as many cigarettes as men are."