Female nurses who work frequent night shifts may be at greater risk for certain cancers, according to a new study.
Chinese researchers compared data from 61 studies, including more than 114,000 cancer cases and more than 3.9 million participants from North America, Europe, Asia and Australia. They found that long-term night work in women increased their risk of cancer by 19%, according to data published in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research.
The results were particularly pronounced among nurses, according to the study. Nurses who worked frequent night shifts had a 58% higher risk of breast cancer, 35% higher risk for gastrointestinal cancer and 28% higher risk for lung cancer, compared to those who didn't work the night shift, researchers found. And nurses had the highest risk of developing breast cancer of all the jobs included in the study.
This echoes previous research that found nurses who often work night shifts face a higher risk for heart disease, workplace injuries and lung cancer. A study published in 2015 found that frequent night shifts increased nurses' risk for all causes of death by 11%.
"Nurses that worked the night shift were of a medical background and may have been more likely to undergo screening examinations," said Xuelei Ma, Ph.D., oncologist at West China Medical Center of Sichuan University in Chengdu, China and one of the study's authors, in an announcement.
"Another possible explanation for the increased cancer risk in this population may relate to the job requirements of night-shift nursing, such as more intensive shifts," Ma added.
Overall, women who work frequent night shifts saw their risk for skin cancer increase by 41%, risk for breast cancer increase 32% and risk for gastrointestinal cancer increase by 18%, according to the study. When the researchers compared these results by region, they found that the risk of breast cancer only increased among North American and European women.
Researchers hope the results will pave the way for greater protections for women who work regular night shifts, including nurses, and to draw more public attention to the issue.