What difference does it make to you?
I see a lot of global warming style “science” here that doesn’t express anything more than belief.
Most pets have considerably shorter lifespans than humans and the likelihood of disease increases with age. I don’t smoke now but I had plenty of pets and none ever developed cancer till one I had long after quitting. I’ve only had one dog that managed to develop 2 different types of cancer in her old age and I got her long after I quit smoking. The first was a cancer of the nerve sheath in her leg that was surgically removed and then she developed pancreatic cancer which killed her about 2 years later.
In dealing with my dog’s cancer I discussed it extensively with my vet and she claims that most cancers in dogs are due to genetic predisposition rather than environmental factors because of their shorter lifespans. They generally don’t live long enough to develop diseases resulting from environmental factors unless the environmental factors are rather severe.Things like lung size are completely meaningless.