Lack of sleep
Lack of sleep increases risk of aggressive breast cancer.

Lack of sleep increases the risk of developing most aggressive breast cancer. Scientists from the University Hospitals Case Medical Center and Case Comprehensive Cancer Center at Case Western Reserve University have found a link between insufficient sleep and biologically more aggressive tumours as well as likelihood of cancer recurrence.

A study conducted on more than 400 post-menopausal breast cancer patients found the link. During the study, scientists analysed medical records and survey responses from 412 post-menopausal breast cancer patients treated with Oncotype DX, a widely utilised test to guide treatment in early stage breast cancer by predicting likelihood of recurrence, at UH Case Medical Centre.

Scientists also asked the participants about their average sleep duration in the last two years.

The study 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 compared to women, who sleep for longer hours.

"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 Cheryl Thompson, Assistant Professor at Case Western Reserve University School of Medicine.

Thonpson claims that fewer hours of sleep per night can increase breast cancer recurrence, specifically in post-menopausal breast cancer patients. This suggests that lack of sufficient sleep may cause more aggressive tumours, but more research will need to be done to verify this finding and understand the causes of this association.

"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, researcher at UH Case Medical Center. "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,"