If you don’t smoke and yet you’ve been diagnosed with lung cancer, you need to figure out whether you are living in a house with elevated radon levels. Radon is the 2nd most common cause (after smoking) of lung cancer. The only way to do something about it, is to fix your housing situation, as you are inhaling radon gas everyday.
“Radon in homes and risk of lung cancer: collaborative analysis of individual data from 13 European case-control studies” - read it here: https://pubmed.ncbi.nlm.nih.gov/15613366/
“Iowa radon lung cancer study” - click here to read it.