While the number of smokers in the world as a proportion of the population is dropping, lung cancer continues to cause almost 2 million deaths per year – and new research reports on a concerning rise in cases among people who've never lit up a cigarette.
The international team behind the research found that rates of lung cancer in this group of people could be tied to increasing levels of pollution and the subsequent damage to health, with east Asia, particularly China, the worst affected.
"As lung cancer is the leading cancer worldwide, a comprehensive understanding of the changing epidemiological patterns and their potential causes is essential," write the researchers in their published paper.
Digging into statistics from the Global Cancer Observatory (GLOBOCAN) survey of 2022, as well as other registers of cancer incidence covering the years 1988 to 2017, the researchers identified adenocarcinoma as the most prevalent type of lung cancer worldwide, accounting for 45.6 percent of cases in males and 59.7 percent in females.
Adenocarcinoma starts in glands, and while it can certainly be caused by smoking, it's not the number one cancer type in smokers. It is, however, the most common type of lung cancer in non-smokers.
Cross-referencing their findings with previous studies, the researchers identify a rising trend in lung cancer cases in people who've never smoked. That's something that needs addressing, the researchers say, along with continuing efforts to get smokers to quit and to discourage young people from taking up the habit in the first place.
"As smoking prevalence continues to decline in many countries worldwide, the proportion of lung cancer in people who have never smoked has increased," write the researchers.
"Notably, lung cancer in people who have never smoked is estimated to be the fifth leading cause of cancer-related mortality worldwide, occurring almost exclusively as adenocarcinoma and most commonly in women and Asian populations."
The research team suggests that part of the reason behind the increasing occurrences of lung cancer in non-smokers is rising air pollution, and several earlier studies have already joined the dots between adenocarcinoma and air pollution.
Again there's a link to east Asia and especially China, where air quality is some of the worst in the world.
Even as one cause of lung cancer is on the wane, another is rising up, and this one is less about personal lifestyle choices and more about global pollution.
As always, frequent data gathering and analysis should give scientists a better understanding of how lung cancer is developing – and how we might continue to tackle one of the most common cancers worldwide.
"Our findings provide insight for those seeking to develop and implement strategies to control tobacco and air pollution that are adapted to populations with high rates of lung cancer incidence or increasing generational risks," write the researchers.
The research has been published in The Lancet Respiratory Medicine.