Within just five years of quitting cigarette smoking, women enjoy a reduced risk of coronary heart disease and a lowered risk of death from cancers related to smoking by about 20%. These are the findings from an extensive observational study, the Nurses’ Health Study, involving 104,519 females followed from 1980 to 2004.

During the course of the study, 12,483 deaths occurred. Of them, 35.9% (4,485) occurred among people who had never smoked, 28.9% (3,602) among those who currently smoked, and 35.2% (4,396) had been smokers in the past.

Analysis of the research revealed an important 13% risk reduction for all causes of mortality within the first five years after quitting cigarettes as compared to those who continued to smoke. After 20 years of not smoking, the past smokers enjoyed the same decreased level of overall risk as those who had never smoked. The risk for vascular diseases declined rapidly within the first five years after quitting.

Within the first five years after quitting, the mortality rate from coronary heart disease dropped by 61% while the risk of death from cerebrovascular disease dropped by 42%. Death from respiratory disease dropped by 18% within the first five to 10 years after quitting and dropped to the same rate of risk as never smokers after 20 years’ abstinence.

Lung cancer dropped by 21% during the first five years after quitting but remained a risk for as long as 30 years after quitting cigarettes. The risk of lung cancer in women who had quit smoking 20 to 30 years earlier was reduced by 87% when compared to current smokers and the risk rate dropped to that of non-smokers after 20 cigarette-free years.

The study indicates that the risks are greater for women who start smoking at earlier ages. Smoking is also associated with an increase in risk of death from colorectal cancer but not for ovarian cancer.

Overall findings reveal 64% of the deaths in smokers were associated with smoking and 28% of the deaths in previous smokers were also associated with the habit.

The research team urges continuation of tobacco prevention programs in schools throughout the country since the greatest risk is faced by women who start smoking earliest. They also suggest risk awareness and prevention programs become an essential component of public health strategies.

According the the World Health Organization (WHO), death occurred prematurely for almost 5 million smokers in 2000. Projections for 2030 point to 3 million tobacco-related deaths in the industrialized countries of the world and an additional 7 million such deaths in developing countries. The WHO maintains the leading cause of preventable death in the US is the use of tobacco products.

The current study, led by Stacey A. Kenfield, ScD, of Harvard’s School of Public Health in Boston, has published her team’s findings in the May 7 issue of JAMA and Archives Journals.