Wny? I should distinguish that there is an "association" of smoking
" and all urothelial, and maybe renal parenchymal cancers.
. . Not the same as cause. Epidemiologists study populations that smoke and match with those that do not smoker, try to "adjust" for other variables. Tobacco produces carcinogens, and that could be the "how", but the science of that is not as well described as with lung.