Researchers from Sichuan University (Chengdu, China) have conducted analyses which imply that long-term night shift work among women may be a risk factor for developing certain cancers.
A meta-analysis was performed using data from 61 articles, comprised 114,628 cancer cases and 3,909,152 participants from around the world. The articles consisted of a mixture of study types, including 26 cohort studies, 24 case-controlled studies and 11 nested case-control studies.
The trials were analysed for an association between long-term night shift work and 11 cancer types. Further analysis was conducted to specifically examine the risk of six types of cancer in female nurses who worked night shifts.
Results demonstrated that overall, female long-term night shift workers had an increased risk of cancer of 19%. The risk of developing skin cancer was 41% higher than in the general population, with risk of breast and gastrointestinal cancers being 32% and 18% higher respectively.
Remarkably, the increased chance of developing breast cancer amongst female nurses was 58%, with an increased risk of 35% for gastrointestinal cancer and 28% for lung cancer, compared with female nurses who did not work night shifts.
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Interestingly, the increased risk of breast cancer was only observed amongst nurses from North America and Europe, which the authors believe may be linked to increased levels of sex hormones in women living in these regions.
Overall, these results indicate the need to examine working habits as potential disease risk factors, highlighting how long-term night shift work must be monitored more closely in order to protect workers. The team hope that their analysis draws attention to these needs, allowing for additional studies to be carried out which may influence policy and screening measures in the future.
“Breast cancer is the most diagnosed cancer among women worldwide, with higher incidence in developed regions,” study lead Xuelei Ma from the West China Medical Center of Sichuan University, concluded. “These results might help establish and implement effective measures to protect female night shifters. Long-term night shift workers should have regular physical examinations and cancer screenings .”