The associations between diurnal cortisol slope, perceived health, perceived stress, and quality of life among breast cancer patients

Abstract

Background: Breast cancer patients are prone to experience psychological distress, disturbed circadian cortisol rhythm, and poorer quality of life. This study attempted to investigate the HPA-axis functioning in terms of the diurnal cortisol slope and its associations with perceived health, perceived stress, and quality of life among breast cancer patients. Methods: Participants were 162 Chinese breast cancer patients (mean age = 49.2 years, SD = 8.1; average cancer duration = 23.0 months, SD = 7.8). They completed the Perceived Stress Scale, Hospital Anxiety and Depression Scale, and Functional Assessment of Cancer Therapy – Breast Cancer and provided 5 salivary cortisol samples upon awakening, at 45 minutes post-awakening, 1200, 1700, and 2100. Latent growth modelling with a latent time basis was used to model the cortisol trajectory and derive the diurnal slope. Results: The latent growth model with latent time basis fitted the data well (χ2(6) = 3.86, CFI = 1.00, TLI = 1.05, RMSEA = .00, SRMR = .035). The participants reported an initial cortisol mean of 7.45 nmol/L and a diurnal decrease of 5.92 nmol/L. Significant interindividual variations existed in the initial level (SD = 2.87) and the diurnal decrease (SD = 2.83). Controlling for age, cancer duration, and awakening time, the diurnal slope was significantly associated with perceived health (β = .48, SE = .21, p < .05), perceived stress (β = .20, SE = .10, p < .05). The diurnal slope was not significantly associated with anxiety (β = -.11, SE = .14, p = .45), depression (β = -.08, SE = .13, p = .54) and quality of life (β = .01, SE = .03, p = .96). Conclusion: Breast cancer patients with poorer perceived health and greater perceived stress showed a flatter diurnal cortisol slope, suggesting a manifestation of anomalous HPA axis activity. Acknowledgement: This study was supported by the Research Grants Council General Research Fund (HKU745110H).