Rotating night shift work and colorectal cancer risk in the nurses’ health studies
Summary
This prospective cohort study combined nearly 191,000 participants from the Nurses’ Health Study and NHS II to assess whether rotating night-shift work raises colorectal cancer risk. After 24 years of follow-up, researchers found no overall link between night-shift duration and colorectal cancer. However, in detailed analysis of cancer subtypes, women with 15+ years of rotating night work had a significantly higher risk of rectal cancer (HR 1.60). Risks for proximal and distal colon cancer were not significantly elevated.
Why It Matters For Night Shift Workers and Night Owls
For nurses and other long-term night-shift workers, this study suggests that decades of rotating night work may increase the risk of rectal cancer, even if overall colorectal cancer rates do not rise. The findings add to evidence that chronic circadian disruption can shape long-term health outcomes. This highlights the importance of preventive strategies, including stable scheduling where possible and regular cancer screening, especially for workers with many years of night duty.
Notes
Journal: International Journal of Cancer, 2018.