Image: On October 26, 2007, Beijing, China, the panoramic view of the Forbidden City was covered in smog. The International Olympic Committee (IOC) warned that due to severe air pollution in Beijing, some outdoor activities might face delays.(Photo by Guang Niu/Getty Images)
People News - A study released by the World Health Organization's cancer agency on February 3 pointed out that since 2000, lung adenocarcinoma has become the most common type of lung cancer worldwide. In China, most of the cases are linked to air pollution, which has drawn significant attention.
According to a report from Radio Free Asia, data published by the International Agency for Research on Cancer (IARC) in The Lancet Respiratory Medicine journal shows that China has the highest number of lung adenocarcinoma cases due to environmental particulate pollution. In 2022, nearly 70% (68.1%, or 77,952 cases) of the global 114,486 male cases came from China. For Chinese women, 70.4% (56,586 cases) of the global 80,378 female cases were attributed to air pollution.
Charles Swanton, a clinical professor at the Francis Crick Institute in the UK, who discovered EGFR gene mutations causing lung cancer in non-smokers in 2022, told Voice of America that it is still unclear why EGFR mutations are so prevalent in Asia. "One of our theories is that air pollution is a factor contributing to the prevalence of these mutations," he said.
Swanton further explained, "Our lab's data shows that in normal tissues exposed to air pollution, EGFR-mutant clones are more likely to be found. This suggests that these clones preferentially expand in lungs damaged by particulate matter, as if air pollution creates fertile soil for these 'seeds' (EGFR mutations) to grow."
Smoking Remains the Biggest Risk Factor for Lung Cancer
However, Swanton reminded that smoking remains the biggest risk factor for lung cancer. He said, "Smoking increases the risk of lung cancer by about 30 times." The risk from air pollution is much smaller, likely less than three times (or at least ten times lower than tobacco exposure), "depending on where you live on Earth. The current problem is so severe because far more people are exposed to air pollution than to tobacco smoking."
The World Health Organization's research indicates that as smoking rates have declined in many countries, the proportion of lung cancer cases among never-smokers has increased, making it the fifth leading cause of cancer-related deaths, almost entirely consisting of lung adenocarcinoma, with a higher prevalence in women and Asian populations.
Moreover, by 2019, approximately 99% of the global population lived in areas where air quality did not meet standards. For instance, in China, the annual average concentration of PM2.5 was 30 micrograms per cubic meter, and PM10 was 54 micrograms per cubic meter, far exceeding the recommended values for PM2.5 (5 micrograms per cubic meter) and PM10 (15 micrograms per cubic meter). Additionally, using solid fuels for heating and cooking is also a cause of lung cancer in non-smoking Chinese women. In 2017, more than 30% of Chinese households still used solid fuels for heating and cooking.
How to Screen for Lung Cancer in Non-Smoking Populations
As for how to detect lung cancer early to extend survival rates, Dr. Norman Edelman, a consultant at the American Lung Association and a professor at the State University of New York Medical School, told Voice of America that a computed tomography (CT) scan is very effective: "Before CT scans, only 15% of lung cancer patients survived for 5 years. Now, if detected early through CT scans, at least 25% of patients can survive for 5 years."
In July 2024, the National Health Commission of China issued a lung cancer screening program using low-dose spiral CT for high-risk populations, such as those aged 50 or older with a smoking history or who have lived or worked with smokers for over 20 years. These individuals can undergo at least one low-dose spiral CT scan annually.
Swanton noted that the reason this type of screening is common worldwide but not extended to a wider non-smoking population is not only due to policy issues but also because the likelihood of developing lung cancer from smoking is still much greater than from any other factor. "From the lung cancer incidence rate in non-smokers, which is fewer than 10 cases per 100,000 people, it’s impractical to screen 100,000 never-smokers each year and find just 10 or 20 cancer patients. That would be a severe waste of resources."
Swanton added that his laboratory is conducting research on how to screen for lung cancer in non-smokers, with potential progress within the next 18-20 months.
In China, the smoking population has significantly decreased compared to the 1990s, but according to previous reports, lung cancer has become the leading cancer in China since 2007, surpassing liver cancer in 2012 as the leading cause of cancer mortality. The 2022 report from the National Cancer Center of China showed that out of 2.574 million cancer-related deaths, 733,300 were due to lung cancer, and 316,500 were due to liver cancer.
According to data from the Chinese Centers for Disease Control and Prevention and the Global Adult Tobacco Survey (GATS), the adult smoking rate in China decreased from 28.1% in 2010 to 24.1% in 2022. In 2019, the smoking rate among Chinese males aged 15 and above was 49.7%, a decrease of 18.2% compared to 1990, while the female smoking rate was 3.5%, a decrease of 20.9% compared to 1990.
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