Depression and IL-6 blood plasma concentrations in advanced cancer patients.

The authors explored the relationship between depression and interleukin-6 (IL-6) blood plasma concentrations among advanced-stage cancer patients. Seventy-three patients with advanced cancer were rated on depression with the Hamilton Rating Scale for Depression and gave blood to be assayed for blood plasma concentration of IL-6. Initial results found no correlation between depression and IL-6. Subsequent analyses found that among those whose blood was drawn within 48 hours of interview completion, depression and IL-6 were highly correlated. Future studies focusing on the relationship between immune functioning and depression must be particularly vigilant regarding methodological issues.