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Night Shift Work Increases The Risk Of Cancer Among Women

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For some, working night shifts is ideal, especially if they aren’t keen on nine-to-fives. Typically, it includes higher pay, plus other benefits such as time during the day to get on top of errands.

But with its benefits also comes disadvantages. A new study published in the Cancer Epidemiology Biomarkers and Prevention journal shared that women who work night shifts are 19 percent more likely to develop cancer.


Study author Dr Xuelei Ma, an oncologist from West China Medical Center at Sichuan University, and her team did a meta-analysis to work out whether working night shifts for a long duration of time increased the risk of women getting 11 different types of cancer.

They looked at 61 articles that involved 114,628 cancer cases and 3,909,152 individuals located in North America, Europe, Asia, and Australia.

The study suggested that women who had late-night occupations for a long period of time were at a 41 percent greater risk of being diagnosed with skin cancer, 32 percent greater risk of breast cancer, and 18 percent greater risk of gastrointestinal cancer. What’s more, every five years of late nights was tied with a 3.3 percent rise in breast cancer risk. 

Past studies have shown that exposure to light at night could potentially increase one's risk of breast cancer, especially if there’s lack of melatonin production by the pineal gland, which could increase the release of estrogen near the ovaries.


In the latest study, when looking at female nurses alone, the scientists noted that there was a 58 percent higher risk of breast cancer for long-term night shift work. Researchers also saw a 28 percent increase in risk of lung cancer and a 35 percent increase in gastrointestinal cancer.

A limitation of this study is an unclear definition of “long-term” night shifts, which includes “working during the night” and “working at least three nights per month.”

Ma also noted in a statement: "Nurses that worked the night shift were of a medical background and may have been more likely to undergo screening examinations. 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."


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