A case-control study of smoking and bladder cancer risk: emergent patterns over time

jnci.oxfordjournals.org JNCI | Articles 1553 Cigarette smoking accounts for about 65 % of bladder cancer risk in men and 20 % – 30 % in women ( 1). Studies have consistently shown a two- to threefold risk of bladder cancer among regular cigarette smokers, defined as those who smoked at least one cig-arette per day for at least 6 months, compared with those who never smoked ( 1). Experimental evidence has suggested that 2-naphthylamine and 4-aminobiphenyl may be the bladder car-cinogens in cigarette smoke ( 1 – 8). Numerous studies have demonstrated that bladder cancer risk increases with increasing duration and intensity (cigarettes per day) of smoking, although risk levels off at higher intensity but not at higher duration ( 1, 9). Bladder cancer risk decreases as time since quitting increases ( 10 – 12), but it is unclear whether risk eventually returns to that of never-smokers ( 1). Moreover, previous bladde