Smoking as a Cause of Bladder Cancer

Whenever I speak to anyone who knows anything about bladder cancer that I had been diagnosed with the same, the first question I am asked is whether I ever smoked? 

My answer:  No, not one day in my life.

However, I did live on the second floor of a two family home for 15 years where the tenant/landlord on the first floor was a heavy smoker.

Does anyone have an educated opinion whether this circumstance may have been a contributing factor?

Jkrief,

Identifying any individual's "cause" of bladder cancer is an impossible task. Even for the most likely or suspected causes that have been investigated, there is no direct link. All that can be said is that a particular risk makes it X-times more likely that an exposed person will develop bladder cancer. It takes a large group of similarly situated individuals to arrive at any such association.

Best,
Jack