Lies, Damn Lies, and Health Canada Statistics

Dubious statistics adorn a pack of Canadian duMaurier Cigarettes.

Picking through trash under the dumpster of a local restaurant last month, I came across this interesting item. It is a box of du Maurier cigarettes that was ostensibly discarded by a Canadian tourist. A couple things about it jumped out at me.

First was the rather large image of what was purported to be lung cancer. I could tell it was an image of lung cancer because the image was captioned “lung cancer”, and a pair of arrows singled out a pair of fleshy, tumorous growths. The following boldface warning accompanied the image:

WARNING: CIGARETTES CAUSE LUNG CANCER

OK. So I’m just going to say: If a person started smoking these cigarettes after this warning started appearing on Canadian cigarette packs and then sued the cigarette company because s/he developed lung cancer, I would defend the cigarette company. I really would.

The second thing that jumped out at me were the statistics written below the image:

85% of lung cancers are caused by smoking.
80% of lung cancer victims die within 3 years.

Health Canada

“Health Canada” should have quit while it was ahead. If it really wanted to demonstrate to me the perils of cigarette smoking–that CIGARETTES CAUSE LUNG CANCER–it certainly chose the wrong statistic.

I think most healthy smokers are interested in knowing: “What are the chances that I’ll get cancer if I start smoking or continue to smoke?” This isn’t what the statistic tells. The statistic says that, given a particular person already has lung cancer, there is an 85% chance that smoking caused cancer in that person. The statistic says nothing, however, about the chances that a smoker will get cancer in the first place.

Maybe only very few smokers ever get cancer, but of those who eventually do get it, it’s very likely that smoking caused it.

It seems to be clear that smoking at least increases the risk of getting cancer, but whether your odds of getting cancer by smoking is anywhere near 85% is impossible to say from the information given. I suspect that “Health Canada” chose the statistic with the higher number for scare purposes–but maybe not. Maybe everyone who smokes gets lung cancer and the other 15% of people who get lung cancer are non-smokers. Who knows?

Anyway. All I’m saying is that they could have chosen a more informative statistic to put on cigarette boxes….