UB study finds no association between sleep duration, breast cancer prognosis

Does the amount of sleep that breast cancer survivors get each night affect their odds of surviving?

A new study led by UB researchers sought to examine the sleep duration and mortality link in a sample of more than 800 breast cancer survivors in Western New York. They report that sleep duration was not associated with death, either from breast cancer or another cause among these women previously diagnosed with breast cancer.

In recent years, scientists have honed in on trying to understand whether sleep plays a role in the progression of cancer, particularly breast cancer. Some studies have reported evidence of an association between the amount of sleep that breast cancer survivors get each night and their risk of dying, either from the cancer or other causes. Researchers believe that sleep duration impacts circadian function in breast cancer survivors, thus potentially influencing disease progression.

“Given that evidence of associations of mortality risk were observed for shorter and longer sleep in other studies, we thought we would have seen similar findings,” explains Nisha M. Nair, lead author on the study published Aug. 18 in the journal Cancer Causes & Control.

“However, we also have to keep in mind that there were some differences between our study and those studies, including differences in the study populations and the way the different studies categorized sleep duration,” says Nair, a graduate student in the Department of Epidemiology and Environmental Health, School of Public Health and Health Professions.

For this study, researchers looked at a sample of 817 patients from Western New York, all with invasive breast cancer who participated in the Western New York Exposures and Breast Cancer (WEB) Study. They were followed for an average of nearly 19 years. During that time, 339 patients died — 132 specifically from breast cancer.

Participants reported on their usual sleep pattern. Shorter sleep was defined as getting five hours or less per night, while longer sleep was nine hours or more. Sleep duration was measured before the breast cancer diagnosis, a key difference from most previous studies, many of which only measured sleep duration after diagnosis.

“We found no associations between pre-diagnostic sleep duration and mortality in this cohort,” Nair says. “We also found no statistically significant interaction with body mass index or tumor stage for either all-cause or breast cancer-specific mortality. This is important because our findings differ from other studies where associations between sleep duration and mortality have been observed.”

While the current study didn’t find any associations, Nair notes that future research investigating pre- and post-diagnostic assessments of sleep patterns among women with breast cancer is needed to add to the understanding of a role, if any, that sleep may play in breast cancer prognosis.

Nair’s UB co-authors on the paper include Jo L. Freudenheim, SUNY Distinguished Professor; Jing Nie, research assistant professor; and Heather Ochs-Balcom, associate professor, all of the Department of Epidemiology and Environmental Health.

Additional co-authors are Maurizio Trevisan, former dean of the College of Health Sciences at Vin University in Vietnam and a former dean of UB’s School of Public Health and Health Professions; and Caila B. Vaughn, an epidemiologist with the New York State Department of Health.