Background In 2007, the International Agency for Research on Cancer classified “shift work leading to a disruption of circadian rhythm” as probably carcinogenic to humans raising a great interest in understanding the role of night/shift work in hormone-related cancers. An association with breast cancer has been suggested while the association with prostate cancer is still controversial and less investigated. In this context, we examined the role of night/shift work in prostate cancer risk based on data from the EPICAP study.

Methods EPICAP is a population-based case-control study conducted in the department of Hérault in France including 819 prostate cancer cases newly diagnosed in 2012–2013 in men <75 years old and 879 controls who were of the same age as the cases. Participants have been face-to-face interviewed by research clinical nurses through a standardised questionnaire on their socio-demographic characteristics, personal and family medical history, lifestyle, leisure activities and complete lifetime occupational history with details on work schedules (permanent or rotating night work) for each job held for more than 6 months. Permanent night work was defined as at least 270 hours/year or 3 nights/month during 1 year or more.

Results The prevalence of night work was 32% and 34% among cases and controls, respectively (OR = 0.86, 95% CI = 0.67–1.09). Neither duration of night work, nor the number of nights worked (total and average/week), nor the type of night work (early morning start, late evening end or working overnight) were associated with prostate cancer risk. Similarly, we did not find any association with prostate cancer aggressiveness according to Gleason score.

Conclusion Currently, our results did not support any association between permanent night work and prostate cancer risk. However, analyses on the association with rotating night work are still in progress.