0435 Feasibility of Dose-Varied CBT-I, Associated Sleep Continuity Trajectories, & Adherence in Breast Cancer Survivors

Introduction Insomnia is a common and persistent concern among breast cancer survivors, often continuing well beyond active treatment. Although Cognitive Behavioral Therapy for Insomnia (CBT-I) improves sleep continuity, the optimal dose of the intervention in oncology settings remain unclear. This study assessed the feasibility of a multi-dose CBT-I protocol and examined trajectories of sleep continuity, and adherence over the course of treatment. Methods Breast cancer survivors aged 25–85 (n=28; 78.6% White), within 6 years of completing treatment, were enrolled. Eligible participants endorsing clinically significant insomnia and fatigue (85.7% insomnia+fatigue) were randomized to one of four CBT-I dose groups (4, 8, 10, or 12 sessions). All treatment was delivered weekly via HIPAA-compliant telehealth by a CBT-I clinician. Primary outcomes included feasibility metrics: recruitment [goal, n=60] & retention (enrolled through final session) and adherence (deviation [minutes] between prescribed & actual time-in-bed and stimulus-control schedules). Exploratory outcomes included diary-derived sleep latency (SL), wake after sleep onset (WASO), and early morning awakenings (EMA). Group differences in sleep continuity over time were evaluated with a GEE model. Secondary models tested group differences in adherence. Results Recruitment goals were successfully achieved, with 61 participants enrolled. With respect to retention, approximately half of the subjects were subsequently disenrolled due to factors such as cancer recurrence, psychosocial stressors, loss to follow-up, and the discovery of medical comorbidities (e.g., newly identified sleep apnea). Of the remaining participants, 35 initiated the study protocol, and 28 ultimately completed the trial. With respect to sleep continuity, GEE models demonstrated significant time effects, with reductions in SL, WASO and EMA across all groups (all β_time < 0, p < .001). Finally, with respect to adherence, dose did not moderate differences in groups, indicating parallel trajectories across randomized groups (all interaction p > .10). Conclusion A multi-dose CBT-I protocol is feasible for breast cancer survivors. Preliminary results suggest that across all groups, participants showed statistically significant improvements in sleep continuity over time (i.e., they fell asleep faster, spent less time awake during the night, and had fewer early awakenings). However there is no effect of CBT-I dosage on adherence. Analyses are ongoing. Support (if any) 1R21CA27098701