ASPO Abstracts
Sleep Duration and Mortality Among Breast Cancer Survivors in the Western New York Exposures & Breast Cancer (WEB) Study
Category: Survivorship & Health Outcomes/Comparative Effectiveness Research
Conference Year: 2021
Abstract Body:
OBJECTIVE: With prevalence estimated at >3 million breast cancer survivors in the US, investigating mortality risk
factors in this group is of public health importance. Sleep and breast cancer incidence have been studied.
However, research among breast cancer cases regarding sleep and survival remains limited.
METHODS: We examined breast cancer cases in a population-based, prospective cohort study, the Western New
York Exposures and Breast Cancer Study with mortality status follow-up using the National Death Index through
December 31, 2018. Cox proportion hazards ratios (HR) with 95% confidence intervals (CI) were used to estimate
risk of overall and breast cancer specific mortality (BCS) for self-reported usual sleep duration categories (short,
recommended, or long, ≤5, 6-8, or ≥9 hours (h), respectively) after adjustment for age, race, education, body mass
index (BMI), menopausal status, ages at first birth & menopause, pack-years of smoking, tumor stage, estrogen
(ER) and progesterone receptor (PR) status. BMI split at the median (27.4 kg/m2), menopausal status and ER
and PR status were examined for effect modification.
RESULTS: Participants were followed for a median of 22 years. While there were no significant associations of
sleep duration with overall survival (OS), there was a non-significant trend toward higher BCS risk for women who
sleep ≥9 compared to 6-8 h/night (HR: 2.29, 95% CI: 0.99-5.32). Among postmenopausal women, ≤5 h of sleep
was associated with a 2.9-fold higher BCS risk; there was no association of long sleep with BCS or OS. Among
those with BMI ≤27.4 kg/m2, short sleep was associated with higher BCS risk; long sleep was associated with
higher risk of BCS and OS. Sleep was not associated with BCS or OS for women above the median BMI. Long
sleep was associated with OS among ER+ but not ER- cases; however, interaction was not significant. For BCS
risk, there was a significant interaction of ER status and sleep duration (p=0.02), but CIs included the null.
CONCLUSIONS: We found some evidence that sleep duration is associated with BCS and OS, particularly among
women who are postmenopausal, with BMI ≤27.4 kg/m2, and/or have ER+ tumors. Further exploration of sleep
duration and prognosis following breast cancer diagnosis is warranted.
Keywords: sleep duration; breast cancer survival