When a smoker dies, six out of 10 times the reason for that death is the smoking. But we now know that this death spiral can stop when a smoker quits.
There's no getting around it, smoking is the deadliest of bad habits. And it's also one of the hardest to change. But most people who try to quit, can eventually do it.
Liz Riley smoked for 30 years. In 2002, with the help of an addiction counselor, she was finally able to quit.
"Immediately, I noticed the effects," she said. "Even within the first few days, I noticed that I could breathe better."
"Once you remove the carcinogens from tobacco smoke from your body, your body is able to repair itself," said Dr. Stacy Kenfield, of the Harvard School of Public Health.
Dr. Kenfield and her colleagues have analyzed how removing the carcinogens from a woman's body after years of smoking changes the risks she faces.
They analyzed the reports of 100,000 women, all nurses, between 1980 and 2004.
They compared how the current smokers, former smokers and non-smokers did in diseases specifically known to be caused by cigarettes.
They found that the risk of dying decreased significantly once women in the study stopped smoking.
"Within the first five years of quitting smoking, we saw a 21 percent reduction in the risk of dying of lung cancer and a 50 percent reduction in the risk of dying of cardiovascular disease, specifically coronary heart disease," Dr. Kenfield said.
It is proof from the study that reducing the risk means adding years to one's life. That is good news for Riley and all former smokers.
"I can't stress enough that it's never too late to stop smoking," Riley said.
It is, indeed, never too late, and especially never too late to try quitting again. Sometimes, it takes different quitting methods to find the one that works. It takes about 20 years for the risk of heart attack and stroke to drop to the same level as someone who has never smoked.
