The Copenhagen case-control study of bladder cancer: role of smoking in invasive and non-invasive bladder tumours.

A population based study of 388 cases of bladder cancer including papillomas and 787 controls in Greater Copenhagen confirmed the role of smoking in the aetiology of bladder cancer. Significantly increased relative risks were found for persons who had smoked only cigarettes (RR = 2.9; both sexes combined) and for mixed smokers including cigarettes (RR = 3.6; both sexes combined). Multiple logistic regression analysis showed significant influences of the amount (pack years) of cigarettes smoked and a reduced risk among persons who had stopped smoking. No significant effects of smoking pipe or cigars/cigarillos were apparent, and the present study does not confirm previous suggestions of associations between the smoking of cigars/cigarillos and bladder cancer in Denmark. Only a slight increase in relative risk with the amount smoked was found. The influence of smoking on bladder cancer risk was similar for tumours in stages T1 and T2-4 at diagnosis and also for tumours of grades 1-2 and grades 3-4 at diagnosis.