Night Shift Linked to Raised Risk of Ovarian Cancer03/15/13
FRIDAY, March 15 (HealthDay News) -- Working at night might do
more than throw your schedule out of whack, researchers warn. Women
who cover the night shift may be at increased risk for ovarian
cancer, according to a new study.
The investigators also found that the risk of ovarian cancer may
be lower for night types ("owls") than for morning types
The study included more than 1,100 women with the most common
type of advanced ovarian cancer, including about 390 with
borderline disease, and more than 1,800 women without ovarian
cancer. The women were aged 35 to 74, and worked in fields
including health care, food service and office administration.
Nearly 27 percent of the women with invasive cancer had worked
nights, compared with about 32 percent of those with borderline
disease and about 22 percent of those without ovarian cancer, the
Working night shifts was associated with a 24 percent increased
risk of advanced cancer and a 49 percent increased risk of early
stage cancer, according to the study, which was released March 14
in the journal
Occupational and Environmental Medicine.
Only women 50 and older were significantly more likely to have
ovarian cancer if they had worked nights, study author Parveen
Bhatti, of the Fred Hutchinson Cancer Research Center in Seattle,
said in a journal news release.
Of the women in the study who had worked night shifts, 27
percent said they tended to be night owls and 20 percent said they
were morning larks. The risk of advanced ovarian cancer was higher
among larks than among owls (29 percent versus 14 percent), as was
the risk of borderline disease (57 percent versus 43 percent).
The researchers suggested that the increased cancer risk in
women who work night shifts could be associated with the hormone
melatonin, which regulates reproductive hormones, particularly
estrogen. Melatonin is normally produced at night but is suppressed
Previous research has suggested that night-shift work may be
associated with an increased risk of breast cancer.
Although the study found an association between night-shift work
and increased risk of ovarian cancer, it did not prove a
The American Cancer Society outlines the
risk factors for ovarian cancer.
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