Probabilities of developing cancer halve at least 15 years after Quit smoking

A major study has revealed that quitting smoking at any age can help to reduce the risk of cancer. The study found that the most significant drop in cancer risk occurred after the first decade of quitting. People who had quit smoking for at least 15 years had their chances of developing cancer halved, compared to those who continued to smoke. The risk of lung cancer fell even further and faster, especially for those who quit smoking before middle age. For this study, researchers examined medical data from almost 3 million Koreans who had undergone health examinations from 2002 onwards. The data included records of cancer cases, such as lung, liver, stomach, and colorectal tumors, until 2019. Throughout the study, almost 200,000 participants received a diagnosis of cancer.

“Regardless of age, quitting smoking has been shown to reduce the risk of developing cancer, especially lung cancer, with early cessation before middle age leading to significant reductions,” said Dr Jin-Kyoung Oh, who led the study at the National Cancer Center near Seoul.

According to a recent study published in Jama Network Open, people who quit smoking have a lower risk of developing lung, liver, colorectal, and stomach cancers compared to those who continue smoking. The study followed up with participants for an average of 13 years and five months. The findings showed that the risk of lung cancer fell by 42% among quitters, whereas smaller decreases of 27%, 20%, and 14% were observed for liver, colorectal, and stomach cancers, respectively.

In the UK, cancer is responsible for over 25% of all deaths annually, with lung cancer being the most prevalent type. At least 15 different types of cancer, including those affecting the lungs, bladder, stomach, and organs like the kidneys and liver, are caused by smoking. Tobacco use is the primary preventable cause of cancer and mortality in the country.

The risk of lung cancer dropped by 57% during the follow-up period for individuals who quit smoking before the age of 50, as per the study. In comparison, the risk of those who continued to smoke remained the same. For those who quit smoking at 50 years or above, there was a 40% reduction in the risk of lung cancer over that time.

“Quitting smoking, no matter your age, can have significant health benefits,” Dr Oh told the Guardian. “Individuals who quit smoking after middle age had a 40% lower risk of developing lung cancer compared to those who continued smoking. Don’t think it’s too late. We encourage you to consider starting your journey to quit smoking.”

The development of cancer is a multi-stage process, with DNA mutations mounting up until one or more cells are damaged in a way that leads them to replicate uncontrollably, said Robert West, professor emeritus of health psychology at University College London and an expert on addiction. The further the smoker is along that pathway when they stop, the greater the chance they will end up developing cancer.

“This study confirms two crucial facts,” West said. “One is that it can take many years for the risk of cancer to decrease relative to continuing smoking. The other is that the decrease is greater for those who quit at a younger age.”

“For smokers, this shows how crucial it is to stop smoking as young as possible. There is a benefit at every age but, the younger smokers can stop, the more of their lives they get back,” Prof West added. “The way out of smoking is clear: try to stop at least once a year and make use of evidence-based specialist stop-smoking support at every quit attempt rather than trying to go cold turkey.”
Malcolm Clark, senior prevention policy manager at Cancer Research UK, said: “Smoking remains the leading cause of cancer, causing around 150 cases across the UK every single day – and the majority of people who smoke have tried to quit.

“It’s never too late to stop smoking, but people need support to help them quit. That’s why we support the UK government’s increased funding for stop-smoking services and the upcoming legislation to change the age of sale of tobacco. If implemented, this could help stop the next generation ever becoming addicted to tobacco.”

Quitting smoking reduces cancer risk. Even early cessation before middle age helps reduce the risk, especially for lung cancer.

This news is a creative derivative product from articles published in famous peer-reviewed journals and Govt reports:

1. Park E, Kang H, Lim MK, Kim B, Oh J. Cancer Risk Following Smoking Cessation in Korea. JAMA Netw Open. 2024;7(2):e2354958. doi:10.1001/jamanetworkopen.2023.54958
2. Doll  R, Peto  R.  The causes of cancer: quantitative estimates of avoidable risks of cancer in the United States today.   J Natl Cancer Inst. 1981;66(6):1191-1308. doi:10.1093/jnci/66.6.1192
3. Gandini  S, Botteri  E, Iodice  S,  et al.  Tobacco smoking and cancer: a meta-analysis.   Int J Cancer. 2008;122(1):155-164.
4. US Department of Health and Human Services. Smoking cessation: a report of the Surgeon General. 2020. Accessed January 2, 2024.
5. Altieri  A, Bosetti  C, Talamini  R,  et al.  Cessation of smoking and drinking and the risk of laryngeal cancer.   Br J Cancer. 2002;87(11):1227-1229. doi:10.1038/sj.bjc.6600638

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