Night shift work and breast cancer risk (review)
Summary
This evidence update reviewed six cohort and four case-control studies published since 2019 on night shift work and breast cancer. Taken together, the new studies provide some support that breast cancer risk may be higher with many years or high frequency of night shifts, but results are not consistent and many studies were small. The update did notadd clear answers about whether risk differs by menopausal status, chronotype (morning/evening preference), tumor hormone subtype, or genetic factors. Overall, the authors conclude the new data somewhat strengthen the earlier evidence but better, longer-term studies with precise exposure measures are still needed.
Why It Matters For Night Shift Workers and Night Owls
For people who work nights, this review is a snapshot of where the science stands: the strongest signal of risk shows up with long-running or frequent night work, but the picture isn’t definitive and important questions remain. Knowing that research is pointing to duration and intensity of night shifts helps frame discussions about work patterns and personal risk awareness, without assuming that any single factor determines outcome. It’s a reminder that the evidence is evolving, and that clearer answers will depend on future studies designed to pinpoint who is most affected and under what scheduling conditions.
Notes
Open access.