At least 20% of people who develop lung cancer are nonsmokers, according to Catherine Madaffari, M.D.
Notes on verification
Multiple independent, reputable medical sources (Mayo Clinic, UChicago Medicine, Yale Medicine, peer-reviewed NCBI article) corroborate that roughly 10-20% of lung cancer cases occur in nonsmokers, supporting the claim.
Sources
- Anyone With Lungs Can Get Lung Cancer (newsnetwork.mayoclinic.org)
- https://www.uchicagomedicine.org/cancer/types-treatments/lung-cancer/non-smokers-and-never-smokers (uchicagomedicine.org)
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7618360/ (ncbi.nlm.nih.gov)
- https://www.yalemedicine.org/conditions/lung-cancer-in-nonsmokers (yalemedicine.org)