Occupation and Risk of Bladder Cancer: A Population Level Comparison of Nordic Countries and Canada

Abstract

Background/Aim: Associations with bladder cancer have been observed for more than 40 occupations. While some findings have been consistent, others have been inconsistent or limited. Outside of the Nordic countries, only few countries have directly linked information on cancer and census data. The aim of the study was to compare occupational variation of the risk of bladder cancer in the Nordic countries and Canada. Methods: In the Nordic occupational cancer study (NOCCA) 73,653 bladder cancer cases were observed during follow up of 141.6 million person years. In the Canadian Census Health and Environment Cohort (CanCHEC) 8,170 cases were observed during 36.7 million person years of follow up. Standardized incidence ratios (SIR) with 95% confidence intervals (CI) were estimated for 53 occupations in the NOCCA cohort and hazard ratios (HR) with 95% CIs were estimated for 42 occupations in the CanCHEC cohort. Results: Elevated risks of bladder cancer were observed among hairdressers, printers, sales workers, plumbers, painters, miners, and laundry workers. Teachers and agricultural workers had reduced risk of bladder cancer in both cohorts. Chimney sweeps, tobacco workers and waiters had about 1.5-fold risk in the Nordic countries; no risk estimates for these categories were given from the CanCHEC cohort. Conclusions: We observed different occupational patterns in risk of bladder cancer in Nordic countries and Canada. The only occupation with similarly increased risk was observed among sales workers. Differences in smoking across occupational groups may explain some, but not all, of this variation.