We have had many cats in this household with two smokers. Three of our cats lived to 20-23 years of age, others died for different causes at normal age but not a single one got lung cancer. Now I have a rescue cat sneezing from allergies, she spent 4 years at the shelter where certainly they were not smoking. I am trying to provide for her as clean an environment as possible and force myself to go and smoke outside. If there is any truth in this, I am not going to make her miserable.
Bless you and your furbaby.