Objectives: The risk of prostate cancer among shift workers was examined in the present industry-based retrospective cohort study.
Methods: The study was established based on a health-care database from a Japanese manufacturing corporation. Work schedules of 4995 male workers (mean age = 55.5 years) were followed up retrospectively; mean follow-up period = 25.0 years. Of the subjects, 4168 had previously undertaken only daytime work (daytime workers), whereas 827 had undertaken rotating three-shift work for >80% of their career (shift workers). All subjects had undergone prostate-specific antigen (PSA) testing. Prostate cancer incidence data were obtained from the health insurance records of 13 daytime and four shift workers. Multivariate logistic regression was used to estimate the relative risk of prostate cancer for the two groups with adjustments for age, body mass index, alcohol intake, smoking, exercise and marital status.
Results: Compared with daytime workers, shift workers showed a non-significant increase in the risk of prostate cancer (odds ratio = 1.79; 95% confidence interval = 0.57, 5.68; P-value = 0.32).
Conclusions: Some increase in the risk of prostate cancer for shift workers was observed, although the result was not statistically significant as a result of the small number of cases. To identify the prostate cancer risk among shift workers, longer-term follow up, including the period after retirement, is required.
© 2011 The Japanese Urological Association.