I have an aunt who is approx. 80 years old who once smoked many years ago, developed lung cancer in her later years and has had a full recovery following treatment.........She is one amazing woman......
But to answer your question, why do people who have never smoked develope lung cancer or emphysema anyway?
Some people get fat, some people don't, some people are allergic to latex, most people aren't.
I'm thinking that the medical and scientific community are now getting too big for their britches..........
The largest cohort of cancer victims in the world are chinese women who cook oily foods over stoves in their homes. Inadequate ventilation.