Cigarette smoking and cancer of the pancreas: Evidence from a population‐based case‐control study in Toronto, Canada

Results are reported with respect to smoking data from a population‐based case‐control study of pancreatic cancer conducted in Toronto, Canada, between 1983 and 1986. Lifetime smoking histories were obtained for 249 cases and 505 controls. A statistically highly significant positive association was observed between lifetime cigarette consumption and risk of pancreatic cancer. There was a rapid decrease in risk with time for those who quit cigarette smoking, the risk for ex‐smokers being the same as for lifetime non‐smokers between 10 and 15 years after quitting. Limiting exposure to the 15 years prior to diagnosis considerably strengthens the association and leads to a much more clearly defined dose‐response relationship with relative risks of 1.88, 4.61, and 6.52 for tertiles of consumption for current cigarette smokers compared with lifetime non‐smokers (p trend < 10−5). We conclude that the current data, together with those from previous studies, strongly support a causal relationship between cigarette smoking and risk of pancreatic cancer, and indicate that cessation of smoking is likely to prove a rapidly effective preventive measure for this major type of cancer.