An international research published in the European Journal of Epidemiology found that women who work night shifts are more likely to get breast cancer, the risks being accentuated in pre-menopausal women.
Canadian, Australian and European scientists surveyed over 13,000 women aged between 55 and 59 years from Australia, Canada, France, Germany, and Spain. Among the respondents, 6,093 women experienced breast cancer while 6,933 healthy women represented the researchers’ control group.
The findings of this study revealed that the risk of developing breast cancer rose with the amount of time worked at night, but also with the number of years spent working night shifts.
Women who had at least three hours of work each night from midnight to five in the morning recorded a 12% higher risk of developing breast cancer than women who had never worked nights. In the of pre-menopausal women, the risk of developing breast cancer was even higher, amounting to 26%.
Working night shifts exposes women to a higher risk of breast cancer
Additionally, the study also found that pre-menopausal women who work over 10 hours per night have a 36 percent greater risk of breast cancer than those who have never worked nights. The risk rose to 80% in women who had worked more than 10 hours per night for over three nights a week.
“The risk associated with breast cancer and working night shifts varied little among participants, regardless of the type of work. Although we are not entirely certain, we believe that the risk could be related to the hypothesis that night work disrupts the circadian rhythm and inhibits the secretion of melatonin, which could protect against cancer,” said Anne Grundy, researchers at the University of Montreal, and one of the study’s co-authors.
The authors of the study also stressed that more research is required to better assess the differences in risk between post- and pre-menopausal women.