Disruption of circadian rhythms (the body’s 24-hour clock) has been identified as a probable carcinogen to humans, based mainly on studies of shift work and breast cancer. Shift work and other circadian disruptors can negatively interrupt the sleep-wake cycle, which is reflected in lower blood levels of melatonin, the hormone that helps regulate sleep. This project is evaluating a laboratory test that measures melatonin levels in blood donated by 50 healthy postmenopausal women. Once the melatonin test has been validated, we plan to use the test to study whether low levels of melatonin in blood are related to risk for postmenopausal breast cancer in a future large study.
Esther John, Ph.D.
Ann W. Hsing, Ph.D. (Stanford University), Frank Z. Stanczyk, Ph.D. (University of Southern California), Allison Kurian, M.D. (Stanford University), Kai Yu, Ph.D. (National Cancer Institute)
Stanford Cancer Institute