Cigarette smoking and bladder cancer: an epidemiological inquiry in West Yorkshire.

Results are given of a case-control study on bladder cancer in West Yorkshire. The aim of the study was to assess what risks exist for cigarette smoking in the United Kingdom and also to investigate if a dose response effect was present. The study shows for the first time in the United Kingdom a positive but weak relationship between cigarette smoking and bladder cancer. Close examination of the data with regard to this effect shows that a complex set of relationships result when the quantity smoked and the period of smoking are taken into account. A dose response effect is weakly demonstrated when a medium quantity of cigarettes are smoked but it is not present at all in those who smoked most cigarettes for the longest periods. No risk appears to exist for those who have smoked only filter cigarettes. The results are contrasted with similar studies and the significance of the observations are discussed.