Related Experiment Video
Updated: Jun 3, 2026

In Vitro Bioluminescence Assay to Characterize Circadian Rhythm in Mammary Epithelial Cells
Published on: September 28, 2017
Rotating night shift work and risk of ovarian cancer
Elizabeth M Poole1, Eva S Schernhammer, Shelley S Tworoger
1Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA. nhlip@channing.harvard.edu
Background:
Night shift work has been associated with higher risks of breast and endometrial cancer, but few studies have evaluated associations with other reproductive cancers.
Methods:
We examined the association between rotating night shift work and risk of ovarian cancer during 20 years of follow-up in 181,548 women participating in two large cohort studies, the Nurses' Health Study (NHS) and NHSII. Number of years of rotating night shift work was queried in 1988 for NHS and in 1989, 1991, 1993, 2001, and 2005 for NHSII. We used Cox proportional hazards regression to model HRs and 95% CIs of ovarian cancer for each shift work category (1-2, 3-5, 6-9, 10-14, 15-19, and 20+ years).
Results:
We confirmed 718 incident cases of ovarian cancer over 2,974,672 person-years of follow-up. Rotating shift work was not associated with ovarian cancer risk in either cohort individually. Combining both cohorts, compared with women without any night work, the HR for 15 to 19 years of rotating night shift work was 1.28 (95% CI: 0.84-1.94) and for 20+ years 0.80 (95% CI: 0.51-1.23).
Conclusions:
In this large prospective study, there was no association between duration of rotating night shift work and risk of ovarian cancer.
Impact:
Although associated with other cancers, night shift work does not appear to be associated with increased risk of ovarian cancer. However, further exploration of the association between melatonin and risk of ovarian cancer is warranted.
Related Concept Videos
Ovarian Cycle
Hormonal Control of the Ovarian Cycle
Before puberty, the hypothalamus releases GnRH in a low frequency, low amplitude pulsatile manner. This along with the immature hypothalamic-pituitary-gonadal axis activity, results in low estrogen levels and the absence of a fully functional ovarian cycle. At puberty, GnRH secretion increases in both frequency and...
Oogenesis
Circadian Rhythms and Gene Regulation
Ovaries
On the ovarian surface, a layer of cuboidal...
Disorders of the Female Reproductive System
