Night work and breast cancer: A population-based case-control study in France (the CECILE study)
International Journal of Cancer,
Menegaux F et al. – Night work plays a role in breast cancer, particularly in women who started working at night before first full-term pregnancy.
Methods- We examined the role of night work in a large population-based case-control study carried out in France between 2005 and 2008.
- Lifetime occupational history including work schedules of each night work period was elicited in 1232 cases of breast cancer and 1317 population controls.
- Thirteen percent of the cases and eleven percent of the controls had ever worked on night shifts (OR = 1.27 [95% confidence interval = 0.99-1.64]).
- Odds ratios were 1.35 [1.01-1.80] in women who worked on overnight shifts, 1.40 [1.01-1.92] in women who had worked at night for 4.5 or more years, and 1.43 [1.01-2.03] in those who worked less than 3 nights per week on average.
- The odds ratio was 1.95 [1.13-3.35] in women employed in night work for more than 4 years before their first full-term pregnancy, a period where mammary gland cells are incompletely differentiated and possibly more susceptible to circadian disruption effects.
