Biomarkers, fatigue, sleep, and depressive symptoms in women with breast cancer: A pilot study

Purpose/Objectives: To evaluate the changes in reports of fatigue, sleep disturbances, and depressive symptoms and serum cortisol, melatonin, serotonin, and bilirubin during adjuvant chemotherapy in women with breast cancer and to determine whether any correlations exist between the symptom parameters and biomarkers. Design: Prospective longitudinal, correlational, repeated-measures pilot study. Setting: Large southwestern, university-based, National Cancer Institute - designated cancer center. Sample: 22 subjects (11 women with stage II breast cancer receiving adjuvant chemotherapy and 11 cancer-free women who were matched by age, ethnicity, and menopausal status). Methods: Questionnaires (fatigue, sleep, depressive symptoms), wrist sleep actigraphy, and laboratory analysis of serum samples. All subjects (i.e., women with breast cancer receiving chemotherapy and a comparison group of cancer-free women who were matched by age, ethnicity, and menopausal status) were admitted to a general clinical research center for two nights during cycles 1 and 4 for data collection. Main Research Variables: Biomarkers (serum cortisol, melatonin, serotonin, and bilirubin), fatigue, sleep, and depressive symptoms. Findings: Mean fatigue scores of the subjects with cancer were significantly higher than the healthy comparison group. Subjects with cancer had a significantly lower mean actual sleep time compared to the comparison group at cycle 1. No significant difference was found between the groups at cycle 4. Depression scores also differed significantly between the cancer group and comparison group. Select biomarkers changed over time and were associated with subjective parameters of fatigue, sleep, and depressive symptoms. Conclusion: Findings suggest that fatique, sleep, and depressive symptoms are more prevalent in women with cancer than a cancer-free comparison group. Biomarkers changed over time and provide a possible explanatory mechanism for the three related symptoms. Implications for Nursing: Data help to explain a mechanism that may underlie fatigue, sleep, and depressive symptoms and provide a theoretical framework from which to establish evidence-based interventions for symptom management.