Night Shift Work Not Fully Linked to Endometrial Cancer in Postmenopausal Women

A recent study by the Epidemiology of Endometrial Cancer Consortium (E2C2) suggests that there is limited evidence to support night shift work and sleep duration as significant risk factors for endometrial cancer in postmenopausal women. The findings were published in Sleep Medicine Reviews.

The study collected individual data on night shift work and daily sleep duration from a substantial pool of participants, comprising 7,207 cases and 22,027 controls across 11 research studies. The primary focus of the analysis was on postmenopausal women, with a sample size of 6,335 endometrial cancer cases and 18,453 controls. 

The findings indicate a non-significant inverse association between endometrial cancer and night shift work (OR=0.89, 95% CI=0.72–1.09). Importantly, this suggests that night shift work is not a significant risk factor for endometrial cancer in postmenopausal women. This observation held true irrespective of shift type, whether permanent or rotating, and the duration of night work.

Moreover, the study examined the impact of sleep duration on endometrial cancer risk. Categorizations of short sleep duration (less than 7 hours) and long sleep duration (9 hours or more) did not reveal any notable associations with endometrial cancer risk. The respective odds ratios were 1.02 (95% CI=0.95–1.10) for short sleep and 0.93 (95% CI=0.81–1.06) for long sleep. This lack of association held even when analyzing sleep duration in 1-hour increments (OR=0.98, 95% CI=0.95–1.01).

However, a noteworthy exception was found among obese women, where an inverse association emerged for each 1-hour increment of sleep (OR=0.93, 95% CI=0.89–0.98). Despite this exception, the overall conclusion remains that night shift work and sleep duration are not strong risk factors for endometrial cancer in postmenopausal women.

Source:

Frias-Gomez, J., Alemany, L., Benavente, Y., Clarke, M. A., de Francisco, J., De Vivo, I., Du, M., Goodman, M. T., Lipworth, L., Lu, L., Peremiquel-Trillas, P., Petruzella, S., … Costas, L. (2023). Night shift work, sleep duration and endometrial cancer risk: A pooled analysis from the Epidemiology of Endometrial Cancer Consortium (E2C2). In Sleep Medicine Reviews (Vol. 72, p. 101848). Elsevier BV. https://doi.org/10.1016/j.smrv.2023.101848