Smoking and bladder cancer risk and recurrence

Smoking has been shown to be a major modifiable risk factor for bladder cancer. However, apart from distinguishing between current smokers and former smokers, not many detailed analyses have been performed on lifetime smoking behaviour and bladder cancer risk. Furthermore, smoking cessation after diagnosis of bladder cancer could improve bladder cancer prognosis, but this has not yet been studied prospectively over a longer period yet. In this thesis, the current evidence on the association between smoking behaviour (duration, intensity, cessation, passive smoking exposure, cigarette type) and bladder cancer incidence and prognosis has been summarised through several meta-analyses. Furthermore, a prospective study on smoking and bladder cancer recurrence is described as well as a consortium study pooling data from 15 case-control studies to further decipher the interplay between smoking duration and intensity in determining bladder cancer risk. Considering all evidence described in the results chapters of this thesis, it is suggested that duration of exposure to cigarette smoke is most important in determining bladder cancer risk and possibly also recurrence. Also, there does not seem to be any association between exposure to environmental smoke and bladder cancer. To provide more insight in how smoking causes bladder cancer, future studies should consider the possible association between molecular subtypes and smoking behaviours