Emerging research links a lack of sleep to aggressive breast cancers.
The first-of-its-kind study discovered an association between insufficient sleep and biologically more aggressive tumors as well as likelihood of cancer recurrence.
The findings, by physician-scientists from Case Western Reserve University, are published in journal Breast Cancer Research and Treatment.
Led by Cheryl Thompson, PhD, researchers analyzed medical records and survey responses from 412 post-menopausal breast cancer patients treated at UH Case Medical Center with Oncotype DX.
Oncotype DX is a widely utilized test to guide treatment in early stage breast cancer by predicting likelihood of recurrence.
In the study, all patients were recruited upon diagnosis and were asked about their average sleep duration in the last two years.
Researchers found that women who reported six hours or less of sleep per night on average before breast cancer diagnosis had higher Oncotype DX tumor recurrence scores (a score based upon the expression of 21 genes).
“This is the first study to suggest that women who routinely sleep fewer hours may develop more aggressive breast cancers compared with women who sleep longer hours,” said Dr. Thompson, an Assistant Professor at Case Western Reserve University School of Medicine and lead author.
“We found a strong correlation between fewer hours of sleep per night and worse recurrence scores, specifically in post-menopausal breast cancer patients.
â€œThis suggests that lack of sufficient sleep may cause more aggressive tumors, but more research will need to be done to verify this finding and understand the causes of this association.”
The authors point out that while the correlation of sleep duration and recurrence score was strong in post-menopausal women, there was no correlation in pre-menopausal women.
It is well known that there are different mechanisms underlying pre-menopausal and post-menopausal breast cancers.
As such, study data suggests that sleep may affect the development of post-menopausal breast cancer, but not pre-menopausal cancer.
“Short sleep duration is a public health hazard leading not only to obesity, diabetes and heart disease, but also cancer,” said Li Li, MD, PhD, a study co-author.
“Effective intervention to increase duration of sleep and improve quality of sleep could be an under-appreciated avenue for reducing the risk of developing more aggressive breast cancers and recurrence.”