Lets say I did contract some form of cancer, or had tooth loss, or gum disease, or my head imploded, or whatever other supposed assured form of tobacco related destruction. I would never logically conclude that tobacco was the actual cause. As sisyphus said, we are exposed to so many vectors for all these diseases - Food(not just processed, but also anything that has been smoked/browned/charred.. say toast or BBQ), ever present industrial pollution, cell phone radiation, standing with my face pressed against the microwave watching my food cooking, prescription medications, alcohol consumption.. I've met a lot of anti-tobacco folks who wouldn't give a second thought to having a regular beer or a glass of whiskey. They've got just as much evidence that it causes esophageal and pancreatic cancer, along with a host of other issues.. I am also pretty sure a tobacco addiction statistically destroys less families, and kills less innocent bystanders (see *Alcoholism, *DUI Accident related deaths).
The bottom line is that none of it really matters. There is no risk/reward, as I wouldn't live my life at all if I made those sorts of calculations, because the risks virtually always outweigh the rewards if you think on a big enough scale. The odds of me dying in a car crash are astronomically higher than me dying from pipe smoking, or cigar smoking, cigarette smoking, or drinking, even if you combine them all - Yet, I still get into the car every day.
The only reason that people consider risk/reward so frequently and specifically with tobacco, is that there is a very public agenda against it, and social consequences for not obeying. Tally up those tobacco deaths with deaths related to automobiles, and do you think anyone would change their agenda on getting to work in a timely manner? You think the "Truth" people would stage anti-car scenes downtown with a bunch of people mowed down by a rogue Subaru? We humans are the masters at convenience moralism.
Live your life while you can.