Business statistics

That statement alone is not sufficient. If 80% of the population smoked, then the rate of smoking in cancer patients would be no different than the general population. Smoking could also be correlated with income/poverty levels, eating habits, etc. You don't have enough here to make that conclusion.

Cancer is a wide ranging term. I have heard that smokers are less likely to get bowel cancer.

Not saying that's a reason to smoke, the negative effects are overwhelming.