Risk of death from tobacco related diseases or cancers declines dramatically five years after kicking the habit

Women who quit smoking reduce their risk of dying from heart disease and tobacco-related cancers. Researchers at the Harvard School of Public Health analyzed data on 105,000 women over 24 years, taken from the Nurses' Health Study, a long-term survey that began at Harvard in 1976.

Stacey Kenfield is lead author of the new report. She says the data show harm from smoking can be reversed over time to the level of a non-smoker. "For coronary heart disease for example, your risk declines to a non-smokers' risk within 20 years. For all causes it declines at 20 years. For lung cancer it is after 30 years."

Kenfield says scientists observed almost immediate benefits when the women kicked the habit. "We saw a 47 percent reduction in risk for coronary heart disease within the first five years [of quitting] and a 21 percent reduction in lung cancer death within the first five years."

Kenfield says the data also indicate that smoking is more dangerous the younger a woman is when she starts. "If you start before you are 17, you have a 21-fold higher risk than a non-smoker. But if you start after the age of 26 you only have a 9-fold higher risk of dying from lung cancer."

Based on that evidence, Kenfield recommends high schools offer more programs to help students quit. "If you would like to see the whole potential benefit from your cigarette cessation, you really need to quit as soon as possible."

Tobacco is the leading preventable cause of death in the United States. The World Health Organization attributed 5 million deaths to smoking in 2000. That number is expected to climb to 10 million tobacco-related deaths by 2030. Kenfield's study is published in the Journal of the American Medical Association.