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Published on: August 30, 2013
Rotating night shift work and mammographic density
Beata Peplonska1, Agnieszka Bukowska, Wojciech Sobala
1Department of Environmental Epidemiology, Nofer Institute of Occupational Medicine, Lodz, Poland. beatap@imp.lodz.pl
Summary
Rotating night shift work was not significantly associated with increased mammographic density in women. This suggests that breast cancer risk in night shift workers may not be linked to changes in breast density or melatonin suppression.
Area of Science:
- Occupational Health
- Epidemiology
- Endocrinology
Background:
- Night shift work is linked to increased breast cancer risk.
- Artificial light at night and disrupted circadian rhythms, including melatonin suppression, are proposed mechanisms.
- Mammographic density is a known breast cancer risk factor.
Purpose of the Study:
- To investigate the association between rotating night shift work and mammographic density.
- To explore the role of melatonin synthesis disruption in this relationship.
Main Methods:
- A cross-sectional study involving 640 nurses and midwives (ages 40-60).
- Assessed rotating night shift work characteristics and mammographic density using computer-assisted methods.
- Measured 6-sulfatoxymelatonin (MT6s) adjusted for creatinine in urine samples.
- Used regression models adjusted for potential confounders.
Main Results:
- Slight, non-statistically significant increases in mammographic density were observed in rotating night shift workers.
- No significant associations were found between night shift work exposure metrics and mammographic density.
- No association was observed between morning MT6s levels and mammographic density.
Conclusions:
- The study does not support the hypothesis linking rotating night shift work, melatonin suppression, and mammographic density.
- It is unlikely that increased mammographic density mediates the elevated breast cancer risk in night shift working nurses.
