I'm convinced that cancer is largely genetic, with a heavy dose of high levels of carcinogens as a big factor (smoking.)
I, too, know a lot of the "Greatest Generation" who LOVE sweets and fatty foods - I think these foods were even much WORSE in the post-WWII years. These folks are in their 80's and going pretty strong, cancer free.
Greatest Generation folks are in their 90’s, not eighties.
Personally I think cancer is hit or miss. Just something goes wrong. I know a nun who died from lung cancer. From a small village in Mexico and never smoked a day In her life. Not saying smoking is good for you just if you are gonna get it you’re gonna get it.
I know people who have never done anything to cause cancer who’ve had it and watch people who should’ve died young live to 90.
Hit and miss.