Occupational variation in the risk of female breast cancer in the Nordic countries

Abstract

ObjectiveThis study aimed to determine occupational variations in the incidence of breast cancer in the population-based cohort of Nordic Occupational Cancer Study (NOCCA).MethodsThe study included long-term follow-up data from almost 7.5million Nordic women. Participants were assigned to one of the 54 occupational categories based on census records at the ages of 30-64years. Sixty-two thousand cases of breast cancer were identified through record linkages between nationwide cancer registries in Finland, Sweden, Norway, Denmark, and Iceland, followed up between 1961 and 2005. Country-specific standardized incidence ratios (SIRs) with 95% confidence intervals were estimated.ResultsOverall, the highest risk elevations were seen among military personnel (SIR 1.58, 95% CI 1.03-2.32), dentists (SIR 1.43, 95% CI 1.31-1.56), and physicians (SIR 1.35, 95% CI 1.26-1.46). The lowest risks were observed among gardeners (SIR 0.76, 95% CI 0.74-0.78), farmers (SIR 0.80, 95% CI 0.78-0.82), and woodworkers (SIR 0.75, 95% CI 0.70-0.81). Welders, tobacco workers, and painters had higher SIRs for breast cancer diagnosed at age