An investigation into socio-demographic-, health-, and cancer-related factors associated with cortisol and C-reactive protein levels in breast cancer survivors: a longitudinal study

Background Breast cancer survivors (BCS) may exhibit dysregulated patterns of cortisol and C-reactive protein (CRP). The aims of this study were to describe BCS’ cortisol and CRP levels over a 1-year period after treatment, and assess how levels relate to socio-demographic- (age, education level, marital status), health- (body mass index [BMI] category, menopausal status), and cancer-related factors (cancer stage, chemotherapy exposure, time since diagnosis). Methods Participants ( N = 201) provided data at 3 months post-treatment (T1) and again 3, 6, 9, and 12 months later (T2–T5). At T1, participants completed self-report questionnaires and had their weight and height measured by a trained technician. At T1–T5, they provided five saliva samples at awakening, 30 min after awakening, 2:00 pm, 4:00 pm, and before bedtime on two nonconsecutive days to measure diurnal cortisol, and provided capillary whole blood to measure CRP. Data were analyzed using repeated-measure analyses of variance (ANOVAs) and mixed-design ANOVAs. Results Diurnal cortisol and CRP levels fluctuated over time. In univariate models, older age and post-menopausal status were associated with higher cortisol and CRP levels, higher cancer stage and chemotherapy were associated with lower cortisol levels, and higher BMI category was associated with higher CRP levels. In adjusted models, age was no longer associated with CRP levels and shorter time since diagnosis was significantly associated with higher CRP levels. Conclusions Socio-demographic-, health-, and cancer-related factors may help identify BCS at risk of physiological dysregulation who need intervention. Identifying modifiable factors associated with cortisol and CRP will inform cancer care interventions.