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Smoking: How Long After Quitting Does Cancer Risk Decrease?

Published January 1, 2026, 17:13
Smoking: How Long After Quitting Does Cancer Risk Decrease?

A new study published in JAMA Network Open shows that the risk of cancer decreases after 10 years of quitting smoking. The study, which followed over 2.9 million Koreans for 13.4 years, showed that former smokers had a lower risk of cancer compared to current smokers, with a significant reduction in risk for lung, liver, stomach, and colon cancer. The risk of cancer was slightly increased for the first 10 years after quitting, but then decreased over time. After 15 or more years, the risk reached 50% of the risk associated with continued smoking. Particularly significant was the reduction in the risk of lung cancer, which was observed three years earlier than for other types of cancer. The greatest reduction in lung cancer risk was observed in people who quit smoking before the age of 50. Researchers emphasize the importance of promoting smoking cessation and providing appropriate support to those who want to quit, especially at a young age, to reduce the risk of cancer.