For decades, lung cancer was synonymous with smoking. But that association, while still mostly true, no longer tells the whole story. In the United States, between 10% and 20% of patients diagnosed with this disease have never smoked, according to data cited by the Centers for Disease Control and Prevention (CDC) and collected by Regional Cancer Care Associates. Other medical sources, such as the Roswell Park Comprehensive Cancer Center, put the figure in a similar range, between 15% and 20%.

The most striking thing is not only the magnitude of this proportion, but its trend: while the general incidence of lung cancer decreases in the country—a product of lower rates of smoking and improvements in early detection—the portion of cases among “never smokers” grows constantly.

It is also significant that the increasing trend of cases has occurred especially in young women under 50 years of age. Unlike smokers, the most common type in this group is adenocarcinoma.

Increase among Asian American women

One of the findings that most concerns the medical community is the steady increase in cases among Asian American women who have never smoked. A recent study found that the incidence of lung cancer in this group increased about 2% each year between 2007 and 2018, a trend that is especially disturbing because it coincides with the period when rates fell in the rest of the population.

Researchers still cannot explain with certainty the origin of this disparity, although they have several hypotheses related to environmental exposures and specific genetic factors.

From radon to genetic mutations

Unlike lung cancer associated with tobacco, the one that appears in non-smokers has a more diffuse and varied map of causes:

A diagnosis that comes late

The problem is not only that the disease appears in an unexpected group, but that it is usually detected in advanced stages. Current screening programs are designed mainly for people with a long history of smoking, which leaves out a large part of non-smoking patients. This low clinical suspicion delays diagnoses and complicates the prognosis, especially in cases—close to 10% of the total—that occur in people under 55 years of age.

Expanding the early detection criteria could significantly change this panorama: some specialists estimate that doing so would raise the detection rate to 94% and prevent thousands of deaths each year in the country.

Light at the end of the tunnel

Not everything is bleak. Advances in treatments targeting specific mutations have transformed the prognosis for many non-smoking patients over the past two decades.

As oncologist David Carbone explained to Nature magazine, the average survival with conventional chemotherapy was around eight months twenty years ago; Today, with targeted oral therapies, the median survival in selected patients has not even been reached yet, and could approach ten years.

Message from the specialists

Doctors insist on a key point: the risk of lung cancer is never zero, even for those who have never smoked. Dr. John Breard, a thoracic surgical oncologist at Banner MD Anderson Cancer Center, summarizes it directly: quitting smoking or not smoking never substantially reduces the risk, but it does not eliminate it, since there are other factors that can trigger the disease.

This nuance is, perhaps, the main lesson that this trend leaves: lung cancer is no longer a disease exclusive to smokers, and its approach—from research to health policy—begins to have to adapt to this new reality.

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