WASHINGTON -- Women who stop smoking greatly reduce their risk of early death and cardiovascular disease just five years after they quit, according to a new study released in the United States.

The risk of death from smoking-related cancers also declines by about 20 percent over the same period, according to the authors of the study published in the May 7 Journal of the American Medical Association (JAMA).

Researchers detected a 13 percent reduction of all causes of mortality within the first five years of quitting smoking, compared with continuing to smoke.

And they found that, 20 years after quitting, the excess risk fell to the level of a person who never smoked, "with some causes taking more or less time," they said in a statement.

Stacey Kenfield of Harvard School of Public Health, Boston, and colleagues looked at the relationship between cigarette smoking and stopping smoking on total and cause-specific mortality in women by reviewing data from the Nurses' Health Study of 104,519 female participants covering the period from 1980 to 2004.

A total of 12,483 deaths occurred in this group, 4,485 (35.9 percent) among those who never smoked, 3,602 (28.9 percent) among current smokers, and 4,396 (35.2 percent) among women who had smoked in the past but quit.

"Significant trends were observed with increasing years since quitting for all major cause-specific outcomes. A more rapid decline in risk after quitting smoking compared with continuing to smoke was observed in the first five years for vascular diseases compared with other causes," Kenfield said.

"Early age at initiation (to smoking) is associated with an increased mortality risk, so implementing and maintaining school tobacco prevention programs, in addition to enforcing youth access laws, are key preventive strategies," the authors stressed.

"Effectively communicating risks to smokers and helping them quit successfully should be an integral part of public health programs," they said.