Night shift work and female breast cancer: a two‑stage dose–response meta‑analysis
Summary
This meta-analysis combined results from 10 cohort studies and 11 case-control studies, involving more than 15,000 breast cancer cases. The researchers focused on how many years women had worked night shifts, instead of just comparing “ever vs. never” night work. They found that breast cancer risk increased gradually with longer night-shift exposure. In cohort studies, the risk rose about 4% after 10 years and 13% after 30 years. In case-control studies, the risk estimates were higher, showing about a 23% increase after 10 years and nearly 88% after 30 years. Overall, the study strengthens the evidence that the length of night-shift work matters when evaluating breast cancer risk.
Why It Matters For Night Shift Workers and Night Owls
This research suggests that the health risks of night work build up over time. A few years on night duty may not change risk much, but decades of repeated night shifts can raise the chances of developing breast cancer. For night-shift workers, the takeaway is that duration matters:
- Awareness helps: knowing that long-term night work carries added risk can guide personal health choices.
- Screening is key: regular breast cancer screening may be especially important for women with long night-shift histories.
- Policy implications: employers and health systems may need to consider ways to limit prolonged, uninterrupted years of night duty.
This study doesn’t offer direct prevention strategies, but it highlights the value of monitoring health closely if night work is a long-term part of your career.
Notes
Open access (BMC Public Health).