The proportion of people diagnosed with lung cancer who have never smoked (never-smokers) is increasing, with air pollution a “major factor”, according to the World Health Organization’s Cancer Agency (CIRC).
Lung cancer in people who have never smoked is now estimated to be the fifth leading cause of cancer death worldwide, according to the International Agency for Research on Cancer (IARC) (“Global lung cancer incidence according to subtype: new study highlights rising adenocarcinoma rates linked to air pollution“). It occurs almost exclusively as adenocarcinoma, which has become the most prevalent of the four main subtypes of the disease in both men and women worldwide.
Need for urgent monitoring
The findings highlight the urgent need for monitoring the changing risk of lung cancer. Further studies are also needed to identify potential causative factors, such as air pollution, in populations where smoking is not considered the main cause of lung cancer.
Whether the global proportion of adenocarcinomas attributed to air pollution will increase depends on the relative success of future strategies to reduce tobacco use and air pollution worldwide.
Lung cancer is a leading cause of death worldwide. In 2022, an estimated 2.5 million people were diagnosed with the disease. However, the patterns of occurrence by subtype have changed dramatically in recent decades. Of the four main subtypes of lung cancer (adenocarcinoma, squamous cell carcinoma, small cell carcinoma and large cell carcinoma), adenocarcinoma has become the predominant subtype among both men and women, IARC found.
The proportion of lung cancer cases in non-smokers
Adenocarcinoma accounts for 45.6% of global lung cancer cases in men and 59.7% of global lung cancer cases in women in 2022. Adenocarcinoma accounts for up to 70% of lung cancer cases among never-smokers, the IARC said.
While lung cancer incidence rates in men have generally declined in most countries over the past 40 years, rates in women have been increasing.
The proportion of global lung cancer cases in non-smokers is not known, but it is increasing. Scientists are working to learn more about what causes lung cancer, besides smoking.
“We can prevent”
“Air pollution may be a major factor that partly explains the emerging prevalence of adenocarcinoma, which accounts for 53% to 70% of lung cancer cases among people who have never smoked worldwide,” the study says.
The study provides important information about how lung cancer develops and the underlying risk factors, “offering clues about how we can best prevent lung cancer worldwide.”
“Changes in smoking habits and exposure to air pollution are among the major determinants of the changing risk profile of lung cancer incidence by subtype that we see today.
The divergent gender trends in recent generations offer insights for cancer prevention experts and policymakers that seek to develop and implement smoke and air pollution control strategies tailored to high-risk populations.”
Top-10
According to AirVisual, which provides independent air quality information, the top ten cities with “red” air pollution are:
Delhi, India. Bishkek, Kyrgyzstan. Tashkent, Uzbekistan. Dhaka, Bangladesh. Lahore, Pakistan. Yangon, Myanmar. Kathmandu, Nepal. Kolkata, India. Hanoi, Vietnam, and Almaty, Kazakhstan. In Europe, Budapest, Hungary, is the most polluted city.
2030 a milestone year
Scientists say air pollution is a “global health disaster”.
Tougher air quality rules came into force in Europe late last year, aiming to bring the European Union closer to WHO standards by 2030 and requiring member states to monitor pollutants such as fine particles, black carbon and ammonia.
Some countries are taking steps to curb pollution levels, including Denmark, which could become the first country in the world to impose a carbon tax on livestock farming in 2030.
Meanwhile, an updated EU directive gives citizens with pollution-related health problems the right to take legal action against their government if it fails to comply with EU air quality rules.
