The study shows that lung adenocarcinoma has emerged as the predominant subtype in recent years, with increasing risks observed among younger generations, particularly females, in most countries.
Air pollution is the leading cause behind the rise in lung cancer cases among non-smokers, especially women and those living in Southeast Asia, according to a study published in the Lancet.
The study, published in The Lancet Respiratory Medicine journal on World Cancer Day on Tuesday, said that lung cancer in people who have never smoked cigarettes or tobacco is now estimated to be the fifth highest cause of cancer deaths worldwide.
“As smoking prevalence continues to decline in many countries worldwide, the proportion of lung cancer in people who have never smoked has increased,” said the researchers, which included from International Agency for Research on Cancer (IARC) and World Health Organisation (WHO).
“Changes in smoking patterns and exposure to air pollution are among the main determinants of the changing risk profile of lung cancer incidence by subtype that we see today,” said Dr Freddie Bray, Head of the Cancer Surveillance Branch at IARC and lead author of the article.
The researchers analysed data, including those from the Global Cancer Observatory 2022 dataset, to estimate the national-level cancer cases for four subtypes: adenocarcinoma (a type of cancer that starts in mucus-producing (glandular) cells; squamous cell carcinoma (a type of skin cancer); small-cell carcinoma (a rare fast-growing lung cancer), and large-cell carcinoma (a type of lung cancer).
The study shows that lung adenocarcinoma has emerged as the predominant subtype in recent years, with increasing risks observed among younger generations, particularly females, in most countries.
The study also highlights that East Asia, particularly China, estimated the most significant burden of lung adenocarcinoma attributable to ambient particulate matter (PM) pollution. Lung cancer remains the leading cause of cancer incidence and mortality worldwide.
In 2022, there were an estimated 2,480,675 new cases of lung cancer worldwide.
As India has emerged as the world’s most polluted country, experts said that there is a rise in lung cancer among non-smokers. Driven by air pollution and poor air quality, surgical oncologists report an alarming trend where an equal number of smokers and non-smokers now require lung cancer surgeries, with many patients under 50 years of age.
Dr. Ruchi Singh, Radiation Oncology, Asian Institute of Medical Sciences, said, “Lung cancer was once considered a smoker’s disease, but we now see a sharp increase in non-smokers developing lung cancer due to polluted air and exposure to toxic environmental factors. It is critical that we expand access to lung cancer screenings in high-risk populations.”
The Lancet report said that adenocarcinoma accounted for 45.6% of global lung cancer cases among men and 59.7% of global lung cancer cases among women in 2022. Adenocarcinoma also accounted for as much as 70% of lung cancer cases among never-smokers.
Of the estimated 1,572,045 new cases among men (63.4% of the total lung cancer burden in both sexes), 7,17,211 (45.6% of the male lung cancer burden) were adenocarcinoma; 4,61,171 (29.4%) were squamous cell carcinoma (SCC); 1,80,063 (11.5%) were small-cell carcinoma, and 1,01,861 (6.5%) were large-cell carcinoma.
Among women, there were an estimated 9,08,630 new cases of lung cancer worldwide (36.6% of the total lung cancer burden in both sexes), of which 5,41, 971 (59.7% of the female lung cancer burden) were adenocarcinoma; 1,55,598 (17.1%) were SCC, 87,902 (9.7%) were small-cell carcinoma, and 59,271 (6.5%) were large-cell carcinoma.
“This population-based study seeks to better understand variations in lung cancer incidence by place and time according to its constituent subtypes. We examine changes in risk in different countries across successive generations and assess the potential burden of lung adenocarcinoma linked to ambient PM pollution,” said Dr Bray.
“The results provide important insights as to how both the disease and the underlying risk factors are evolving, offering clues as to how we can optimally prevent lung cancer worldwide,” he added.
Article Credit: newindianexpress