Higher than normal plasma interleukin-6 concentrations in cancer patients with depression: Preliminary findings

Objective: This study investigated whether cancer patients with and without major depression exhibit immune system abnormalities similar to those repo rted in medically healthy, depressed subjects without cancer. Method: The study subjects consisted of patients diagnosed with pancreatic, esophageal, or breast cancer. Other groups consisted of subjects with majo r depression (without cancer) and healthy comparison subjects. Subjects' di agnoses were made with the Structured Clinical Interview for DSM-III-R. Sev erity of depression was measured with the Hamilton Depression Rating Scale. Plasma concentrations of interleukin-6 (IL-6) and postdexamethasone cortis ol were measured. Results: Cancer patients with depression had markedly higher plasma concent rations of IL-6 than healthy comparison subjects and cancer patients withou t depression. Although significant correlations were found between Hamilton depression scale scores and plasma concentrations of postdexamethasone cor tisol, no significant correlations were found between plasma IL-6 and postd examethasone cortisol concentrations. Conclusions: Higher than normal plasma IL-6 concentrations were associated with a diagnosis of major depression in cancer patients. IL-6 may contribut e to sickness behavior that has overlapping symptoms with major depression.