Study links long-term night shift work to breast cancer

Kingston, Ontario – Women who have worked the night shift for 30 or more years may have an increased risk of breast cancer, according to a new study from Queen’s University.

As part of the study, researchers examined 1,134 breast cancer cases and 1,179 control cases. Approximately one-third of the women in both groups had been employed in night shift work, and those who were employed in shift work for 30 or more years had double the risk of breast cancer.

Unlike previous studies, which primarily have focused on nurses, in this study researchers looked at a variety of occupations and found the breast cancer risk was not limited to the health care field.

The study was published online July 1 in the journal Occupational and Environmental Medicine.