Sleep disturbance among breast cancer survivors and controls from midlife to early older adulthood: Pink SWAN

Purpose To compare sleep disturbance from 5 years pre- to 5 years post-diagnosis between breast cancer survivors (BCS) and women without cancer over the same period and to identify BCS subgroups exhibiting different sleep trajectories. Methods Analyses included data from 152 BCS and 2163 controls from 20 years of follow-up in the longitudinal Study of Women's Health Across the Nation (SWAN), a multi-racial/ethnic cohort study. SWAN participants were assessed approximately annually from 1995 to 2015 using a standardized protocol. Pink SWAN focused on women who reported no cancer at SWAN enrollment and developed incident breast cancer after enrollment or did not develop breast cancer. Nonparametric locally weighted scatterplot smoothing plots and linear mixed models were used to compare the prevalence of the most frequently reported sleep problem, frequently waking several times a night (a sleep maintenance problem) during the previous 2 weeks, between BCS and controls in the 5 years pre- to 5 years post-diagnosis. We characterized heterogeneity among BCS on this sleep problem using group-based trajectories and examined pre-diagnosis variables as predictors of group membership. Results No differences were found between BCS and controls in prevalence of frequent nighttime awakenings either before or after diagnosis. Among BCS, three trajectory groups were identified. Thirty-seven percent of BCS had consistently low prevalence of waking several times per night, 30% had high prevalence, and 33% had increasing prevalence which started 2 years pre-diagnosis. Prevalence of pre-diagnosis vasomotor symptoms, anxiety, depressive symptoms, and smoking differed among these groups. Conclusion Among mid-aged women diagnosed with breast cancer, this diagnosis did not trigger/amplify a sleep maintenance problem. The majority of BCS had similar levels of this sleep problem from pre- to post-diagnosis. Implications for Cancer Survivors Although sleep maintenance problems were not amplified by a cancer diagnosis, a subset of BCS may have sleep issues that should be monitored and treated, as indicated.