Effect of Psychological Inflexibility and Cancer-Related Dysfunctional Beliefs About Sleep on the Relationship Between Depression and Fear of Progression in Patients with Cancer.

This study examines the relationship between fear of cancer progression and depression in patients with cancer, emphasizing whether psychological inflexibility and cancer-related dysfunctional beliefs about sleep mediate this relationship. We retrospectively reviewed medical records from 170 patients with cancer who visited a Stress Management Clinic between September 2022 and August 2023. Collected data included demographic information and responses to self-reported rating scales, including the Action and Acceptance Questionnaire-II (AAQ-II), Fear of Progression Questionnaire-Short Form (FoP-Q-SF), Patient Health Questionnaire-9 (PHQ-9), State subcategory of the State-Trait Anxiety Inventory (STAI-S), Insomnia Severity Index (ISI), and Cancer-related Dysfunctional Beliefs about Sleep scale (C-DBS). Pearson's correlation, linear regression, and mediation analyses were performed. Higher FoP-Q-SF scores were significantly correlated with elevated PHQ-9 (r = 0.56), STAI-S (r = 0.17), ISI (r = 0.21), C-DBS (r = 0.34), and AAQ-II (r = 0.53) scores. Linear regression analysis showed that FoP-Q-SF scores were significantly associated with younger age (β = -0.25, p < 0.001), higher depression levels (PHQ-9; β = 0.35, p < 0.001), stronger cancer-related dysfunctional beliefs about sleep (C-DBS; β = 0.20, p = 0.002), and greater psychological instability (AAQ-II; β = 0.24, p = 0.002). Mediation analysis indicated that depression directly influenced fear of progression. Furthermore, psychological inflexibility and cancer-related dysfunctional beliefs about sleep partially mediated the relationship between depression and fear of progression. Psychological inflexibility and cancer-related dysfunctional beliefs about sleep mediate the relationship between depression and fear of cancer progression in patients with cancer.