Occupational exposure and smoking adjusted risk of bladder cancer. Population based cohort studies in the Nordic countries.


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Kishor Hadkhale1,Jan Ivar Martinsen2,Elisabete Weiderpass3,Kristina Kjaerheim2,Par Sparen4,Laufey Tryggvadottir5,Elsebeth Lynge6,Eero Pukkala7,Tom K Grimsrud2
1Tampere University, Tampere, Finland,2Cancer registry of Norway, Oslo, Norway,3International Agency for Research on Cancer, Lyon, France,4Karolinska Institute, Stockholm, Sweden,5Icelandic cancer registry, Reykjavik, Iceland,6University of Copenhagen, Copenhagen, Denmark,7Finnish cancer registry, Helsinki, Finland

Abstract

Background

Occupational exposure has been identified as the most important risk factor for bladder cancer second to smoking. The objective of this study was to observe the occupational variation in risk of bladder cancer that is not attributable to smoking.

 

 

 

Method

In the Nordic Occupational Cancer (NOCCA) study, 111,458 cases of bladder cancer cases were observed among men in Denmark, Finland, Iceland, Norway and Sweden during 1961-2005. In this study we used confirmatory factor analysis models for simultaneous analysis of bladder cancer related to tobacco. The unobserved pattern of smoking habits was considered latent common factors. Results was used to compute expected numbers of cancer from reference rates, adjusted for tobacco smoking. Crude and smoking-adjusted SIRs for bladder cancer with 95% confidence intervals (CI) were calculated for the 54 occupational categories as defined in NOCCA.

Results

The smoking-adjusted SIR for virtually all of the occupations was closer to 1.00 than the unadjusted SIR. The highest unadjusted risk among Nordic men was observed among chimney sweeps (SIR 1.49, 95% CI 1.21-1.80), waiters (1.42, 1.25-1.61), hairdressers (1.30, 1.17-1.45), assistant nurses (1.28, 1.09-1.50), seamen (1.22, 1.16-1.28), plumbers (1.20, 1.13-1.28), tobacco workers (1.18, 0.79-1.70), printers (1.18, 1.11-1.26).The risk was closer to 1.00 for almost all the occupations after smoking adjustment. Chimney sweeps (1.21, 0.99-1.47), waiters (1.06, 0.93-1.20), hairdressers (1.10, 0.99-1.22), assistant nurses (1.23, 1.05-1.44), seamen (1.02, 0.97-1.07), plumbers (1.03, 0.97-1.10), tobacco workers (0.98, 0.66-1.40) and printers (1.04, 0.98-1.11). The risk was highest in Denmark while the lowest in Finland.

Conclusion

Smoking is a strong risk factor for bladder cancer but there are also other risk-increasing factors in some occupations signifying the risk due to occupation. The occupational variation in risk of bladder cancer is small when adjusted for smoking.