People who have spent most of their lives smoking may derive health benefits within five years of quitting - drastically reducing their chance of dying from a heart attack, stroke or lung cancer, according to a study published today.
In just five years, quitters reduced their added risk of dying of a heart attack by 47 percent and of lung cancer by 21 percent. Over time, their risk declined to the level of nonsmokers.
The message: There is hope for even the most inveterate smokers.
"Many people think there's just nothing they can do," said Stacey A. Kenfield, an epidemiologist with the Harvard School of Public Health. "But even in the short term, we do see benefit for some diseases, and it's worth it even if you're 70 years old and you've been smoking all your life."
The analysis, published in today's Journal of the American Medical Association, is the most complete picture to date of the health effects of quitting, some experts said.
One hope for quitters is a new vaccine designed to block the pleasure of smoking. At a conference in Baltimore yesterday, the vaccine's Rockville-based maker reported that 16 percent of volunteers in a clinical trial were able to quit after repeat inoculations, compared with 6 percent of those who got a placebo.
About 42 million Americans smoke cigarettes, and 440,000 people die each year from effects of the habit - accounting for one in five American deaths, according to the U.S. Centers for Disease Control and Prevention.
In the Harvard study, researchers followed more than 100,000 female nurses between 1980 and 2004, asking them every two years to answer questions, including their smoking status and history of chronic diseases. The research was part of the Harvard Nurses' Study, one of the largest and longest-running observational studies of risk and women's health.
Among other findings, the researchers learned that people who quit smoking lowered their risk of dying of any cause by 13 percent in the first five years. By the 20th year, their risk was the same as people who had never smoked.
It took 20 years of abstinence to erase the elevated risk of dying from a smoking-related cancer and 15 to 20 years to erase the increased risk of a fatal heart attack. But most of the benefit to the heart occurred in the first five years, in contrast with the lungs, where the benefit occurred more gradually.
