Up to 20% of lung cancers occur in non-smokers

Smoking is considered the main risk factor for lung cancer, a highly prevalent tumor that, unlike breast, colon or prostate, is very lethal: its five-year survival is only 15%.

However, “according to the literature, between 10 and 20% of cases occur in people who have never actively smoked,” explains Dr. Luis Manuel Entrenas, head of the Pulmonology Service at the Quirónsalud Córdoba Hospital.

Specifically, the literature considers non-smokers to be people who have never smoked or who have smoked less than 100 cigarettes during their entire life.

So why is it? Another agent related to lung cancer, especially in non-smoking patients, apart from passive smoking, is exposure to radon. “It is the second carcinogen after tobacco in our environment (having defined population areas with high concentrations of radon in our country) and is the main cause of lung cancer in non-smoking patients,” says Dr. Javier López González, specialist at the Medical Oncology Service of the Quirónsalud Córdoba Hospital.

This natural radioactive gas, odorless, is more present in certain Spanish geographical areas, since it is released more in permeable soils and in granite areas, so, for example, due to the type of construction, it is common in the mountains. of Guadarrama.

It can also be due to “pollutants associated with different professional activities such as arsenic, some forms of silica, chromium and, especially asbestos», reports the pulmonologist. To them we must add «“exposure to air pollution and family history of lung cancer”adds Trains.

Among both non-smokers and smokers, lung cancer non-small cell is the most common type. Thus, in those who have never had this addiction, “half of the cases usually correspond to lung adenocarcinomas,” says the doctor. A type of cancer that, being non-small cell, usually spreads more slowly than small cell cancer.

However, when tumors are discovered, they are sometimes more advanced than in smokers, since on too many occasions certain symptoms, such as a continuous cough, are downplayed in someone who has never smoked. But “the symptoms are the same in smokers and non-smokers, since we are talking about lung cancer in both cases,” recalls Dr. José Felipe Coll Klein, head of the Pulmonology Service at the Dexeus University Hospital, in Barcelona, ​​who emphasizes that in the case of non-smoking patients “we usually find “special” mutations in adenocarcinomas.”

«Between 10 and 20% of lung cancer cases in non-smokers are squamous cell tumors, also non-small cell tumors. And between 6 and 8% are undifferentiated small cell lung cancers. Lastly, there are a small number of rare tumor types,” details Entrenas.

Regarding the treatment, «surgery is the main surgical option and the one associated with greater survivalas occurs in solid tumors in general,” says the same doctor.

“And, in cases where it cannot be performed with curative intent,” he continues, “radiotherapy or conventional chemotherapy (or both) can achieve prolonged survival.”

To these treatments we must add immunotherapy, “with which we are obtaining magnificent results,” adds Dr. Coll Klein.

«They are mainly monoclonal antibodies that can be directed against the tumor that shows certain genetic profiles. This is what is sometimes known as personalized treatments,” says Dr. Entrenas.

«In terms of the evolution and development of drugs, we do see differences between patients who smoke and never smokers, since in the latter subtypes of lung cancer with driver mutations such as EGFR and ALK are more common, for which we have treatment modalities. directed, which are not generally expressed in smoking patients,” says the oncologist.

Regarding screening, in Spain this test is still not approved for lung cancer, despite being more lethal than breast, cervical and colorectal cancer, for which it is done.

And in the case of non-smokers, “in countries that have it implemented, such as the United States, they do not recommend performing it systematically because the inconveniences of performing periodic chest CT scans on the non-smoking population outweigh the theoretical benefits that would be achieved.” explains Dr. Entrenas.