No Excess Cancer Risk among Veterinarians in Denmark, Finland, Iceland, Norway, and Sweden after the 1980s

DISCLAIMER: Where authors are identified as personnel of the International Agency for Research on Cancer/World Health Organization, the authors alone are responsible for the views expressed in this article and they do not necessarily represent the decisions, policy, or views of the International Agency for Research on Cancer/World Health Organization. SIMPLE SUMMARY: Veterinarians can be exposed to a wide range of known and suspected carcinogens through their work, however relatively few studies have investigated the cancer risk in the profession. We investigated cancer incidence in veterinarians in Denmark, Finland, Iceland, Norway, and Sweden, across more than 40 years. In all the countries, the overall cancer incidence in veterinarians was close to the incidence in the total population. There was an elevated incidence of several cancer types among male veterinarians before the 1990s but no excess cancer risk after that. Veterinary work environments have been changing, and are changing, in terms of exposure to chemical compounds, ionizing radiation from diagnostic imaging, and different pathogens, and these changes may affect the cancer profile of veterinarians. ABSTRACT: The cancer profile of veterinarians has received little research attention, despite the profession potentially being exposed to a wide range of known and suspected carcinogens. In this large-scale cohort study, we assessed cancer incidence in veterinarians in Denmark, Finland, Iceland, Norway, and Sweden, across more than 40 years (1961–2005). The cohort comprised 4708 veterinarians and 119,503 person-years at follow-up. The overall cancer incidence in veterinarians was close to the incidence in the total population in all countries and in all age groups. In male veterinarians, the standardized incidence ratios (SIR) in 1961–1990 were elevated for colon cancer (1.86, 95% confidence interval (CI) 1.39–2.44), prostate cancer (1.35, 95% CI 1.07–1.67), and especially skin melanoma (3.62, 95% CI 2.78–2.84), while there was no longer any statistically significant excess in the more recent follow-up period. Decreased SIRs were observed for lip cancer (0.11, 95% CI 0.00–0.62), laryngeal cancer (0.38, 95% CI 0.12–0.89), lung cancer (0.59, 95% CI 0.47–0.74), and stomach cancer (0.58, 95% CI 0.38–0.86), without a marked change in SIR over time. Non-significant excesses among male veterinarians were also observed in Hodgkin lymphoma (1961–1990 only), and leukaemia. This multi-country study indicates that there was an elevated incidence of several cancer types among male veterinarians before the 1990s but not after that. Some of the findings might rather be attributed to lifestyle factors and not directly to work conditions, but the excess risk of cancers of kidney and bladder, for example, might be related to work exposures.