Shift work and the risk of prostate cancer development

Abstract

Prostate cancer is the second most prevalent cancer worldwide, and there are few established risk factors. Recently there has been focus on shift work and prostate cancer, however epidemiological studies have shown inconclusive results. The aim of my thesis is to investigate how shift work affects the risk of developing prostate cancer in the Tromsø Study. We utilized data from Tromsø4, conducted in 1994-95. Participants were linked to the Cancer Registry of Norway to detect prostate cancer cases. There were 9078 men included, and 685 were diagnosed with prostate cancer during the 25 years follow-up. Multivariable Cox proportional hazard model was used to estimate hazard ratios of developing prostate cancer. The hazard of developing prostate cancer after working shifts was 9% lower compared to those who did not work shifts, adjusted for age (p = 0.37). In our multivariable model, adjusting for several confounders, the hazard of prostate cancer development among shift workers was 10% lower (p = 0.31). In conclusion, we found no significant association between working shifts and developing prostate cancer in the Tromsø Study. Men working shift had a decreased prostate cancer-risk in this study, however the results were not significant. Our study indicates that shift work is not carcinogenic, however more research on the subject is warranted.