I am an oncologist. Here’s what non-smokers need to know about lung cancer.

I always thought that smoking was the main cause of lung cancer. What can cause a non-smoker to develop lung cancer?

This week, the Vatican confirmed that a pulmonary nodule on Pope Leo XIV’s right lung was early-stage lung adenocarcinoma, a subtype of non-small cell lung cancer. Doctors removed the nodule, along with the entire lower lobe of his right lung, during surgery. The pope is not known to be a smoker, although he has a family history of other cancers: both his parents died of cancer and his brother is currently being treated for blood cancer.