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Women who work nightshift may have increased risk of ovarian cancer

Filed in
  • Women
  • Diseases
  • Shift Work

By Lynn Celmer  |  Mar 18, 2013
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A new study has found a link between working the night shift and ovarian cancer.

The study, published in the March issue of Occupational and Environmental Medicine, included 1,101 women with the most common form of advanced ovarian cancer, 389 women with borderline ovarian cancer and 1,832 women that were part of a healthy comparison group.

Among the women with advanced cancer, about one quarter had ever worked the night shift, compared with a third of the women with early-stage cancer and a fifth of the healthy comparison group.

Night shift work was associated with a 24 percent higher risk of advanced ovarian cancer and a 49 percent higher risk of early-stage ovarian cancer, the researchers found. However, the risk of cancer was 7 percent lower in women who described themselves as night types.

"We found evidence suggesting an association between shift work and ovarian cancer," the researchers, led by Dr. Parveen Bhatti, an epidemiology researcher at the Fred Hutchinson Cancer Research Center, wrote in the study. "However, there was suggestive evidence of a decreased risk of ovarian cancer among women reporting a preference for activity during evenings rather than mornings."

Approximately 22,000 women are diagnosed with ovarian cancer every year in the United States, according to the study, and over 15,000 of them will die from the disease. There are very few known risk factors, the researchers wrote in the study, which makes further research to better understand how shift work raises your risk crucial.

The researchers suggested that melatonin, a hormone that is typically produced at night and regulates reproductive hormones such as estrogen, may be to blame for the increased risk. Melatonin suppresses estrogen levels, but is not produced in the presence of ambient light, such as the kind shift workers would be exposed to, according to the study.

To learn more about shift work disorder and other common sleep disorders, visit