Sustained smoking cessation is associated with a reduced risk of cancer after 10 years of quitting, according to a study. study published online at Open JAMA Network.
Eunjung Park, Ph.D., of the Graduate School of Cancer Science and Policy at the National Cancer Center in Goyang, South Korea, and colleagues examined the temporal evolution of cancer risk by time since stopping of smoking in a retrospective cohort study in which 2,974,820 people participated. Korean participants aged 30 or older.
The researchers confirmed 196,829 cases of cancer during an average follow-up of 13.4 years. Those who quit smoking completely had a lower risk of cancer compared with continuous smokers, with hazard ratios of 0.83 for all cancer sites and 0.58, 0.73, 0.86, and 0. 80 for lung, liver, stomach and colorectal, respectively.
The risk of cancer was slightly elevated during the 10 years after quitting smoking compared with continuing smoking and then decreased over time; After 15 years or more, the risk reached 50 percent of that associated with continuing smoking.
The risk of lung cancer decreased three years earlier than that of other cancers, and a larger relative reduction was observed. A greater reduction in lung cancer risk was observed in association with smoking cessation before age 50 years compared with age 50 years or older (hazard ratios, 0.43 and 0.61, respectively).
“Our findings emphasize the importance of promoting smoking cessation, offering adequate support and resources for sustained cessation, and encouraging smoking cessation at an early age to reduce cancer risk,” the authors write.
Eunjung Park et al, Cancer risk after quitting smoking in Korea, Open JAMA Network (2024). DOI: 10.1001/jamanetworkopen.2023.54958
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