Association of IL-6, hypothalamus-pituitary-adrenal axis function, and depression in patients with cancer.

BACKGROUND: Evidence suggests that cytokines (IL-6) and alteration of the hypothalamic-pituitary-adrenal (HPA) axis play a crucial role in the etiology of depression. Patients with cancer show elevated prevalence rates for depression. The objective of this cross-sectional study was to investigate the associations between these abnormalities and depression. METHODS: Plasma concentrations of IL-6 and cortisol were measured in cancer patients with (N = 31) and without depression (N = 83). The relative diurnal variation of cortisol (cortisol VAR), expressed in percentage, was calculated. RESULTS: There was a significant difference in median plasma concentration of IL-6 between the patients with depression and those without (18.7 vs 2.7 pg/mL; P < .001). Relative cortisol VAR was decreased in depressed patients as compared with patients without depression (11.72% vs 60.6%, P = .037). A positive correlation between the depressive symptoms and IL-6 concentration was found (r = 0.469, P < .001). Negative correlations were found between cortisol VAR versus depressive symptoms and cortisol VAR versus IL-6 (r = -0.6, P < .001 and r = -0.52, P < .001, respectively). IL-6 (odds ratio [OR] = 1.1; 95% confidence interval [CI] = 1.0-1.2; P = .006) and cortisol VAR (OR = 1.3; 95%CI = 1.0-1.4; P = .02) are independently associated with depression. CONCLUSIONS: Depression in cancer is associated with increased plasma IL-6 concentrations and dysfunction of the HPA axis.

Biomarkers of depression in cancer patients.

BACKGROUND: Inflammation and perturbation of the hypothalamic-pituitary-adrenal (HPA) axis function appears to play a putative role in the etiology of depression. Patients with metastatic cancer demonstrate elevated prevalence rates for depression. The objective of the current study was to illustrate the efficacy of interleukin-6 (IL-6) and HPA axis function as adjuncts to support the diagnosis of depression in cancer patients. METHODS: Plasma concentrations of IL-6 and cortisol were measured in 114 cancer patients with and without depression. The relative diurnal variation of cortisol (cortisol VAR), expressed as a percentage, was calculated. Receiver operating characteristics analysis was performed. RESULTS: Depression was associated with increased plasma concentrations of IL-6 (18.7 pg/mL vs. 2.7 pg/mL; P < .001) and higher cortisol concentrations at 8 AM and 8 PM. The relative cortisol VAR (11.7% vs. 60.6%, respectively; P < .001) was found to be decreased in cancer patients with depression, indicating a disturbed circadian function of the HPA axis. As a biomarker of depression, IL-6 yielded at a cutoff value of 10.6 pg/mL, a sensitivity of 79%, and a specificity of 87% (area under the curve [AUC] = 0.86; 95% confidence interval [95% CI], 0.78-0.94), whereas cortisol VAR demonstrated a sensitivity of 81% and a specificity of 88% (AUC = 0.85; 95% CI, 0.74-0.97) at a cutoff value of 33.5%. CONCLUSIONS: Depression is associated with increased plasma IL-6 concentrations in patients with cancer. These patients demonstrate a dysfunction of the HPA-axis, characterized by a decreased diurnal variation of cortisol. The high sensitivity and specificity of these parameters biomarkers of depression make IL-6 and cortisol VAR helpful tools in the diagnosis of depression in patients with cancer.