Why do non-smokers also get lung cancer? The latest research finds...

Lung cancer is a relatively common disease, with more than 2 million people diagnosed with the disease every year. Most people with lung cancer have a history of smoking, but 10% to 20% of lung cancer patients have never smoked. Among these never-smoking lung cancer patients, women are more likely to be diagnosed at an earlier age.

Common environmental factors, such as exposure to secondhand tobacco smoke, radon gas, air pollution, and asbestos, may cause lung cancer in a subset of nonsmokers. However, scientists still do not know how most nonsmokers develop lung cancer.

To figure this out, researchers from the National Institutes of Health and its National Cancer Institute conducted a study. They analyzed the genes of lung cancer patients with no history of smoking and found that most tumors were caused by the accumulation of gene mutations in natural processes. They described for the first time three molecular subtypes of lung cancer in never-smokers and published their findings in the journal Nature Genetics on September 6, 2021.

The researchers gave names to the three molecular subtypes of lung cancer based on the number of genomic changes in the tumor. The dominant "piano" subtype has the fewest mutations and is associated with the activation of progenitor cells. Tumors of this subtype grow extremely slowly and are difficult to treat because it can have many different driver mutations. The "mezzo-forte" subtype has specific chromosomal changes, frequent mutations in the receptor gene EGFR, and exhibits faster tumor growth. The "forte" subtype is common in lung cancer patients who smoke, and tumors of this subtype also grow quickly.

The findings help unravel the mystery of lung cancer in people with no history of smoking and may guide the development of more precise clinical treatments. "We also hope that this detective-style investigation of genomic tumor signatures will open up more avenues for discovering new cancer types," said Stephen J. Chanock, MD, director of the Division of Cancer Epidemiology and Genetics.

(Source: Qianzhan.com)