Night work and cancer risk: results from the ELSA-Brasil worker cohort

ABSTRACT

Objective

To estimate the association between exposure to night work and the incidence of breast, prostate, and colorectal cancer among participants in the Estudo Longitudinal de Saúde do Adulto (ELSA-Brasil – Longitudinal Study of Adult Health).

Methods

ELSA-Brasil is a multicenter cohort study conducted in the Northeast, South, and Southeast regions of Brazil. A total of 14,787 participants were included at baseline (2008–2010) and followed through 2023, with a mean follow-up duration of 13 years (SD = 2.22). Exposure to night work was defined based on self-reported occupational history, considering cumulative duration. Incidence cases of cancer were identified during follow-up. Associations were estimated using Cox regression models, adjusted for sociodemographic, behavioral, and occupational variables.

Results

Exposure to night work for more than ten years was associated with an increased risk of prostate cancer (HR = 1.38; 95% CI 1.09–1.75) and colorectal cancer (HR = 1.35; 95% CI 1.09–1.68), compared with exposure to day work. No association was observed between breast cancer and night work (HR = 0.89; 95% CI 0.65–1.22).

Conclusion

The results suggest that prolonged exposure to night work may increase the risk of cancer, particularly prostate and colorectal cancer. This is the first study from the ELSA-Brasil cohort to analyze cancer incidence, expanding knowledge on work-related cancer and reinforcing the carcinogenic potential of night work, with implications for occupational health surveillance and cancer prevention policies in public health.