Breast cancer patients with longer sleep duration face greater mortality risk
Sleep appears to be related to survival among women with breast cancer, according to the 30-year data from the Nurses’ Health Study. Specifically, longer sleep duration, increased sleep duration from pre- to postdiagnosis and sleep difficulties are associated with all-cause mortality.
The study included 3,682 breast cancer patients (mean age at diagnosis 64.9 years; 88.3 percent postmenopausal). Majority (91.7 percent) had stage I or II disease. Average time spent sleeping was self-reported. A subsample of 1,949 women who completed multiple questionnaires provided data on changes in sleep duration from pre- to postdiagnosis, while another subsample comprising 1,353 women completed the sleep difficulties measure.
Multivariate Cox analysis was performed to test the association of various facets of sleep with all-cause, breast cancer and nonbreast cancer mortality.
Of the patients, 965 reported ≤6 hours of sleep per night, 1,234 did 7 hours, 1,100 did 8 hours (reference) and 383 did ≤9 hours. Compared with those in the reference group, women who slept ≤9 hours per night postdiagnosis showed significantly higher risk of all-cause (hazard ratio [HR], 1.37; 95 percent CI, 1.10 to 1.71), breast cancer (HR, 1.46; 1.02 to 2.07) and nonbreast cancer mortality (HR, 1.34; 1.01 to 1.79).
Furthermore, increased sleep duration postdiagnosis and regular sleep difficulties were associated with a significantly elevated risk of all-cause mortality (HR for increased duration vs unchanged, 1.35; 1.04 to 1.74; HR for regular difficulties vs rare/none, 1.49; 1.02 to 2.19) and a moderately greater risk of breast cancer and nonbreast cancer mortality.
The current data suggest that various facets of sleep are associated with greater all-cause mortality among breast cancer patients, and further investigation is warranted to examine the mechanisms underlying such association, researchers said.
“If these results are replicated in future work, it will be important to evaluate breast cancer patients for long and changing sleep duration, in addition to sleep difficulties in the clinical setting, to identify patients who may be at risk for poor outcomes,” they added.
The most common cancer in women globally, breast cancer occurred in about 246,660 women and was attributed to 40,450 deaths in US alone in 2016. Compared with the general population and patients with other cancer sites, women with breast cancer are likely to have poorer sleep quality from diagnosis through treatment and survivorship, and this is regardless of disease stage and position on the cancer trajectory. Disrupted sleep may be linked to the patient’s emotional response to diagnosis and treatment side effects (eg, pain and fatigue). [Cancer Facts & Figures. American Cancer Society: Atlanta, 2016. Psychooncology 2012;21:100–107; J Clin Oncol 2011;29:3580–3586; J Pain Symptom Manage 2011;42:239–250; Ann Behav Med 2013;45:329–337]