Quitting smoking reduces the risk of cancer at any age, according to a study

Quitting smoking at any age helps reduce the risk of cancer, according to a major study, which found that the biggest drop in cancer risk occurred after the first decade of quitting, writes theguardian.com.

The chances of developing cancer were halved in people who had stopped smoking for at least 15 years, compared with those who continued to smoke, with the risk of lung cancer falling even further and more rapidly, especially in those who quit smoking before middle age.

Researchers analyzed medical data from nearly 3 million Koreans who underwent health examinations starting in 2002 and recorded cases of cancer, including lung, liver, gastric and colorectal tumors through 2019. During the course of the study, nearly 200,000 participants had received a cancer diagnosis

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

After an average follow-up of 13 years and five months, the risk of lung cancer among those who quit smoking dropped by 42%, with smaller decreases of 27%, 20% and 14% for liver cancer, colorectal and stomach, respectively, compared to those who continued to smoke. The details were published in Jama Network Open.

Cancer causes more than a quarter of all deaths in the UK each year, with lung cancer being by far the most common. Smoking causes at least 15 different types of cancer, affecting the lungs, bladder, stomach and intestines, as well as organs such as the kidneys and liver. Tobacco is the leading preventable cause of cancer and death in the country.

According to the study, smokers who quit before age 50 had a 57 percent lower risk of lung cancer during follow-up compared to those who continued to puff. Those who quit at age 50 or older saw a 40 percent reduction in lung cancer risk during that time.

“Quitting smoking, regardless of age, can have significant health benefits,” Dr. Oh told The Guardian. “People who quit smoking after middle age had a 40% lower risk of developing lung cancer compared to those who continued to smoke. Don't think it's too late. We encourage you to consider starting your journey to quit smoking.”

Cancer development is a multistep process, with DNA mutations accumulating until one or more cells are damaged in a way that causes them to reproduce uncontrollably, said Robert West, professor emeritus of psychology at of health at University College London and addiction expert. The further the smoker is on this path 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 continued smoking. The other is that the decline is greater for those who quit smoking at a younger age.”

For smokers, this shows how crucial it is to quit smoking as early as possible. There is a benefit at every age, but the sooner smokers can stop, the more they regain their lives.” Professor West added. “The way out is clear: try to quit at least once a year and use specialist evidence-based smoking cessation support with each quit attempt rather than trying to quit from smoking.”

Malcolm Clark, senior manager of prevention policy at Cancer Research UK, said: “No need for a tougher approach: Smoking remains the leading cause of cancer, causing around 150 cases in the UK every day – and most people who smoke have tried to quit. It's never too late to quit smoking, but people need support to help them quit. That's why we support increased UK Government funding for smoking cessation services and future legislation to change the smoking age. If implemented, these measures could help prevent the next generation from becoming addicted to tobacco.”