Risk of bladder cancer by source and type of tobacco exposure: A case‐control study

Abstract

The association between tobacco use and risk of bladder cancer was investigated in a population-based case-control study conducted in Alberta and south-central Ontario, Canada, between 1979 and 1982. In all, 826 histologically-confirmed cancer cases and 792 randomly selected controls, individually matched to cases for age, sex, and area of residence, were recruited into the study. Compared to those who had never smoked cigarettes, males and females who had ever smoked cigarettes had a statistically highly significant 2-fold increase in risk of bladder cancer; for ex-smokers, the risk was intermediate between that for current smokers and never-smokers. There was a dose-dependent increase in risk of bladder cancer with total lifetime cigarette consumption, of similar magnitude for males and females. In males, risk increased with self-reported degree of inhalation in ex-smokers and in current smokers (statistically significant trend), while in females there was no association in current smokers, and a statistically significant inverse association in ex-smokers. Overall, risks of bladder cancer associated with lifetime consumption of plain and filter cigarettes were similar, and there was little evidence to suggest that switching from plain to filter cigarettes was beneficial. Neither passive smoking nor other forms of tobacco consumption (pipes, cigars, chewing tobacco, or snuff) were associated with altered risk of bladder cancer. The population attributable risk for cigarette smoking was about 47% in males and about 33% in females.

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“…However, in two previous case-control studies no excess risk of bladder cancer due to ETS was demonstrated [17,49]. According to Burch et al [17], it is not likely that any association between passive smoking and bladder cancer will be strong, considering that the association between passive smoking and lung cancer also appears to be relatively weak. The present study adds to this body of evidence and endorses these earlier results.…”

“…Therefore, it seems plausible to suggest that individuals exposed to ETS might be at increased risk of bladder cancer [17]. However, in two previous case-control studies no excess risk of bladder cancer due to ETS was demonstrated [17,49]. According to Burch et al [17], it is not likely that any association between passive smoking and bladder cancer will be strong, considering that the association between passive smoking and lung cancer also appears to be relatively weak.…”

“…cigar and pipe) is inconsistent and, when found, generally weaker than the association with cigarette smoking [4,8,10,45]. Despite the plausibility of associations between cigar and pipe smoking and the risk of bladder cancer (since the smoke of both types of tobacco contains many of the same substance as that of cigarette tobacco), it has been suggested that their effect is likely to be small [14,17,46]. In our study almost all men smoked a cigar or pipe in combination with cigarettes; therefore we have adjusted the RRs for cigarette smoking frequency and duration to obtain less biased risk estimates for cigar and pipe smoking.…”

“…Mutagens have been detected in the blood and urine of passive smokers [47,48]. Therefore, it seems plausible to suggest that individuals exposed to ETS might be at increased risk of bladder cancer [17]. However, in two previous case-control studies no excess risk of bladder cancer due to ETS was demonstrated [17,49].…”

“…Although of interest, few studies simultaneously included different smoking characteristics in a regression model to estimate the individual impact of cigarette smoking features. The impact of active cigar and pipe smoking and environmental tobacco smoking (ETS) has also been evaluated less often than active cigarette smoking [13][14][15][16][17][18][19][20][21][22][23][24][25].…”