A Queen’s University and British Columbia Cancer Agency study has determined that Working night shifts for 30 or more years will double the risk of developing breast cancer.
In the past, other research has suggested that shift work as a risk factor for breast cancer – primarily dealing with nurses who work nights – but there has been some doubt about the conclusiveness of those findings, in large part due to issues about the determination of exposure and not capturing the variety of shift work patterns.
“As shift work is necessary for many occupations, understanding which specific shift patterns increase breast cancer risk, and how night shift work influences the pathway to breast cancer, is needed for the development of healthy workplace policy,” said the co-authour of this study, professor Kristan Aronson, in a media release.
The researchers investigated how working night shifts was linked to an increased risk of breast cancer among 1134 women with breast cancer and 1179 women without the disease, but of the same age.
The women – located in Vancouver and in Kingston – who had done a variety of jobs, provided information about their shift work patterns over their entire work history. Hospital records were utilized to determine the type of cancer tumours.
Approximately one in three women in both groups had employment that involved night shifts. No evidence was found that the women who had worked nights either less than 15 years, or between 15 and 29 years, had any increased risk of developing breast cancer. However, those who had worked for 30 years or more were discovered to be twice as likely to have developed the disease.
The link between breast cancer and shift work has been suggested to involve melatonin, but the study’s authors also point to “sleep disturbances, upset body rhythms, vitamin D or lifestyle differences” as also possibily play a part.
The other researchers involved in the study at Queen’s University included Anne Grundy, Harriet Richardson, and Sandip SenGupta. This research was recently published in the journal Occupational and Environmental Medicine.
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Image compilation sources: ribbon – Yongjiet (cc) | night shift – Thomas Lieser (cc)
