Lung cancer is often associated with smoking, but can you get lung cancer if you've never smoked? According to a recent study conducted by the National Cancer Institute (NCI), there is evidence to suggest that a majority of lung cancers in non-smokers are caused by natural processes in the body.
The Study
The study, published in Nature Genetics, used whole-genome sequencing to analyze the genomic changes in tumor tissue from 232 non-smokers diagnosed with non-small cell lung cancer. The researchers discovered three molecular subtypes of lung cancer in non-smokers, each with distinct characteristics and evolutionary processes.
One subtype, called the piano subtype, had the fewest mutations and was associated with the activation of progenitor cells. This subtype grows slowly over many years and is difficult to treat due to the presence of multiple driver mutations. The mezzo-forte subtype had specific chromosomal changes and mutations in the EGFR gene, which is commonly altered in lung cancer. This subtype exhibited faster tumor growth. The forte subtype exhibited whole-genome doubling, a genomic change often seen in lung cancers in smokers. This subtype also grows quickly.
Risk Factors for Non-Smokers
While smoking is the leading cause of lung cancer, accounting for the majority of cases, approximately 10% to 20% of lung cancer cases occur in non-smokers. The exact causes of lung cancer in non-smokers are still unknown, but environmental risk factors may play a role. Exposure to secondhand tobacco smoke, radon, air pollution, asbestos, or previous lung diseases may increase the risk of lung cancer in non-smokers.
The study did not find any mutational signatures associated with direct exposure to tobacco smoking in the tumor genomes of non-smokers. However, the sample size of patients exposed to secondhand smoke was small, and the level of exposure varied greatly. Further research with a larger sample size is needed to fully understand the impact of secondhand smoke on the development of lung cancer in non-smokers.
Implications for Treatment
The identification of molecular subtypes of lung cancer in non-smokers has important implications for treatment. The slow-growing piano subtype may provide an opportunity for early detection and intervention. The mezzo-forte and forte subtypes, with their specific driver mutations, may benefit from targeted treatments.
Further research is needed to study lung cancer in non-smokers from different ethnic backgrounds and geographic locations to better understand the diversity of these tumors and the influence of various risk factors.
While smoking remains the primary risk factor for lung cancer, non-smokers can also develop the disease. The study conducted by the NCI provides valuable insights into the molecular subtypes of lung cancer in non-smokers and highlights the need for further research and personalized treatment approaches.
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