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Quitting Smoking Delivers Health Benefits at Any Age

A person lighting a cigarette.
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Quitting smoking can increase life expectancy after just a few years, suggests a new study from the University of Toronto.

Short- and long-term effects of quitting smoking

There are over a billion smokers worldwide. Though the global rate of smoking has been falling, tobacco is still a leading cause of preventable deaths, responsible for over 8 million deaths each year.

There is strong evidence that quitting smoking can reduce smoking-related illnesses and deaths – but it is unclear how much and how quickly quitting smoking can cut these risks.

Researchers in the current study – published in NEJM Evidence – analyzed data from almost 1.5 million adults over 15 years. There are around 60 million smokers in the 4 countries investigated in the study – the US, the UK, Canada and Norway.

Approximately 123,000 deaths were reported in the 1.5 million-strong cohort. Current smokers had a significantly higher risk of death compared with never-smokers – risks were 2.8-fold higher for women and 2.7-fold higher for men.

Smokers between 40–79 years of age had an almost 3-fold higher risk of dying compared to never-smokers, which translates to losing on average 12–13 years of life.

Quitting leads to health benefits, regardless of age

The study’s findings also revealed benefits for those who quit smoking, even later in life. Former smokers lowered their risk of death down to 1.3-fold (or 30% higher) compared to never-smokers. Stopping smoking at any age was linked to longer survival – even quitting for less than three years led to an increase in life expectancy of up to six years.

People who quit before age 40 had nearly the same life expectancy as never-smokers. Additionally, quitting at any age leads to near never-smoker life expectancy after 10 years smoke-free – and almost half of this benefit came within the first 3 years of quitting.

“Quitting smoking is ridiculously effective in reducing the risk of death, and people can reap those rewards remarkably quickly,” said Prabhat Jha, senior author of the study and a professor at the University of Toronto’s Dalla Lana School of Public Health.

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“Many people think it’s too late to quit smoking, especially in middle age,” explained Jha. “But these results counter that line of thought. It’s never too late, the impact is fast and you can reduce risk across major diseases, meaning a longer and better quality of life.”

Large reductions were observed in the risk of dying from vascular disease and cancer after quitting. There was also a reduced risk of death from respiratory disease among former smokers, but this effect was not as strong, likely due to residual lung damage.

“When smokers interact with the health care system in any way, physicians and health professionals can encourage them to quit, pointing out how well quitting works,” Jha said. “This can be done with concern, and without judgment or stigma, recognizing that cigarettes are engineered to be highly addictive.”

Reference: Cho ER, Brill IK, Gram IT, Brown PE, Jha P. Smoking cessation and short- and longer-term mortality. NEJM Evidence. 2024;0(0):EVIDoa2300272. doi: 10.1056/EVIDoa2300272

This article is a rework of a press release issued by the University of Toronto. Material has been edited for length and content.