My parents were both heavy smokers. In his sixties my father came down with bladder cancer. He survived by quitting smoking entirely and lived to be 93. In her sixties my mother developed a very rough throat that scared the bejeesus out of her. She quit smoking and lived twenty more years.
My parents, heavy smokers, smoked until almost the end. Mother had a severe stroke at 70 and lived as an invalid for 5 more years. High blood pressure from smoking didn’t help. My father also died at 75 of COPD (smoking) and a weak heart. Not sure when he quit if he ever did.
I have some very long lived genes on my fathers side and I am convinced that if he had not smoked he could have been like his aunt and been the oldest person in the US when he died. His aunt lived to be 115 years and 9 months.
Of course they were WW2 era people and they almost all smoked.