Smoking-adjusted risk of kidney cancer by occupation: a population-based cohort study of Nordic men

Background: Evidence suggests that among some occupational groups, there is an elevated risk of kidney cancer. This might, however, derive from a difference in smoking habits across occupational groups. The objective of this study was to determine smoking-adjusted occupational variation in the incidence of kidney cancer in Nordic males. Material and Methods: The source population for this study consisted of 7.4 million men from Denmark, Iceland, Finland, Norway, and Sweden. Data on occupation were obtained from national censuses conducted in the years 1960–1990. Data on cancer cases came from national cancer registries. A proxy for the occupation-specific smoking prevalence among all Nordic men was calculated based on the occupation-specific smoking prevalence and lung cancer incidence data for Finnish men. Smoking-adjusted standardized incidence ratio (SIR_adj) with 95% confidence intervals (95%CI) were calculated for each occupational group. Results: The highest SIR_adj estimates were observed in dentists (1.32, 95%CI 1.06–1.62), journalists (1.20, 95%CI 1.00–1.42), physicians (1.19, 95%CI 1.03–1.36), public safety workers (1.18, 95%CI 1.10–1.26), administrators (1.17, 95%CI 1.13–1.22), military personnel (1.16, 95%CI 1.05–1.28), and religious workers (1.17, 95%CI 1.09–1.26). The lowest SIR_adj was observed among forestry workers (0.82, 95%CI 0.76–0.88). Conclusions: Tobacco smoking plays an important role in the occupational variation in the risk of kidney cancer. The smoking-adjusted incidence of kidney cancer was increased in dentists, physicians, journalists, administrators, and public safety workers.