Is coffee drinking a risk factor for pancreatic cancer, after all? Kuper and colleagues1 argue on the basis of data presented by Porta and colleagues2 that this may be distinct possibility.

Relations between coffee drinking and the risk of pancreatic cancer have been examined in numerous epidemiological studies, with the overall conclusion that there is essentially no association.3 This is also in accordance with two Norwegian prospective studies.4-6

Porta and colleagues found K-ras mutations in 78 per cent of the cases of pancreatic cancer in their dataset.2 The mutation prevalence was directly related to coffee consumption.2 How can it be explained, then, that coffee consumption is not related to the risk of pancreatic cancer? Porta and colleagues,2 and Dr Vineis in the accompanying editorial,7 argue against a causal relation and suggest that substances in coffee may have an impact on the metabolic processes affecting carcinogens and on the DNA repair mechanisms. But, it may be argued, as Kuper and colleagues do: if the result of these processes, alone or in an interaction with, for example, smoking or dietary factors, is pancreatic cancer, then …