In a recent study, researchers from Vanderbilt University Medical Center found that when one quits smoking, the lung cancer risk drops fast within the first 5 years.
The researchers analyzed data from the landmark Framingham Heart Study, and it is published in the Journal of the National Cancer Institute.
In the study, the researchers examined the health records of residents of Framingham, Massachusetts, who have been followed for decades.
Their goal was to help establish high blood pressure and high cholesterol as key risk factors for cardiovascular disease. But the study also tracked cancer outcomes.
The team looked at 8,907 participants who had been followed for 25 to 34 years.
The Framingham study asked people about their smoking every two to four years and could account for increases or decreases in smoking over time.
They found that during this period, 284 lung cancers were diagnosed, nearly 93% of which occurred among heavy smokers.
Heavy smokers were those who had smoked at least a pack of cigarettes a day for 21 years or more.
Five years after quitting, the risk of developing lung cancer in former heavy smokers dropped by 39% compared to current smokers and continued to fall as time went on.
But even 25 years after quitting, their lung-cancer risk remained higher compared to people who had never smoked.
This finding challenges the current federal guidelines, which mandate insurance coverage of lung cancer screening for current and former smokers, exclude those who haven’t smoked for 15 years or more.
But 4 of 10 cancers in heavy smokers in the current study occurred more than 15 years after they quit.
The team suggests that for people who smoke now is a great time to quit. Their lung cancer risk will drop relatively quickly after quitting smoking.
But former heavy smokers need to realize that their risk of lung cancer remains higher for decades after they smoke their last cigarette, and they should consider lung cancer screening.
Further study is warranted to determine whether extending the cut-off point for mandated screening would be cost-effective and save lives, the researchers concluded.
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