Researchers find an association between depression and biomarkers for inflammation, which may mean a poor prognosis.
“Depression levels may be as important or even more important than other factors that have been associated with how people fare with lung cancer,” says Barbara Andersen, Ph.D., professor of psychology at The Ohio State University and lead author of a study that found moderate to severe depression “reliably” predicted outcomes.
The researchers studied 186 patients who were newly diagnosed with stage IV non-small cell lung cancer (NSCLC). They measured biomarkers associated with systemic inflammation: neutrophils, lymphocytes, and platelets, which are all known predictors of survival in NSCLC.
Follow-up ranged from three to 24 months; the median was eight months. At two years, 113 patients (61%) had died. After adjusting for covariates, such as age and smoking, the researchers found depression was reliably associated with biomarker levels. Patients with moderate or severe depressive symptoms were two to three times more likely to have poor biomarker levels.
Although the researchers say it’s unknown whether the depression-inflammation association would remain after cancer treatment started, they found a “trajectory of depression” from diagnosis through two years, with the same systemic inflammation ratios being prognostic for survival.
The patients also filled out a questionnaire about depression, which showed that 35% had moderate to severe depression. “It is normal to be upset, sad and anxious about a cancer diagnosis,” Andersen says, “but it is not normal to have major depression.” The researchers note that many patients with NSCLC also have anxiety, which they note is more resistant to psychological treatment.
Close inspection of the data highlighted differences in the association between depression and inflammation, the researchers say. For instance, the majority of depressed patients had high platelet-to-lymphocyte levels and low Advanced Lung Cancer Inflammation Index levels—double to triple the number of patients without depressive symptoms, and considered “prognostically poor.” Those numbers were “even more compelling,” the researchers note, when contrasted with currently accepted indicators of poor survival: There were more depressed/elevated inflammation patients than patients with low performance status (13%), overweight (29%) and high school education (34%).
“Of all cancer patients, those with lung cancer are among those with the highest rates of depression,” Andersen says, “which makes the findings of our study even more concerning.”
The findings were published in PLoS One in February.