When it comes to the consequences of smoking, you’ll often find chronic obstructive pulmonary disease (COPD) and lung cancer at the top of the list. While it is true that a lifetime of smoking does often lead to such problems, non-smokers who develop COPD could be at greater risk of lung cancer.

A Numbers Game

Such was the conclusion of a 2020 study, published in the journal Thorax. The study authors examined the health histories of nearly 340,000 adults, which were collected by South Korea’s National Health Insurance Service (NHIS). These Korean citizens’ ages ranged from 40 to 84. More than half of these individuals were women, and all had received at least one health check from the NHIS between 2002 and 2013.

Using inpatient and outpatient treatment records, along with prescription history, the research team was able to track the subjects’ health for an average of seven years. Over this timeframe, lung cancer appeared in 1834 adults. Of this figure, COPD was present in 290 cases.

Calculating Risk

Sure enough, lung cancer was a massive problem among both current and former smokers with a history of COPD. Compared to non-smokers, these groups were six times as likely to be diagnosed with lung cancer. Likewise, smokers without COPD were still twice as likely as non-smokers to develop this type of cancer.

But what about non-smokers? The authors determined that those who had previously developed COPD were 2.5 times at risk of lung cancer. In other words, this group’s risk of lung cancer was comparable to smokers who had never been diagnosed with this respiratory condition.

While smoking is the main risk factor for COPD, many people with this condition have no history of smoking. In fact, nearly 40% of COPD sufferers are lifelong non-smokers, and the lung cancer risk of such individuals is still unknown. However, there is some good news; the authors note that “given that poor lung function in COPD is often a barrier to optimal lung cancer treatment due to increased risk of treatment related morbidities, our study suggests that early detection of lung cancer in COPD patients may reduce the risk of treatment complications.”