Elevated C-reactive protein, a marker of systemic inflammation, appeared associated with depression among patients with metastatic lung cancer, according to results of a study published in Cancer.
The results suggest C-reactive protein (CRP) may help identify a subset of patients with lung cancer and depression due to inflammation, as well as help predict responses to treatments that target inflammation or its downstream mediators on the brain.
“Inflammation in lung cancer is associated with depression both in terms of severity and clinical significance,” Daniel C. McFarland, DO, medical oncologist in the department of medicine at Memorial Sloan Kettering Cancer Center, and colleagues wrote. “Both inflammation and depression were elevated and significantly associated in this population of [patients with] lung cancer actively undergoing anticancer treatments.”
Between 16% and 29% of patients with lung cancer experience depression, which exceeds the 15% average in other forms of cancer. Inflammation may contribute to the high rate because it is present in both cases of lung cancer and depression, researchers wrote.
Researchers sought to identify the relationship between inflammation and depression by analyzing 109 patients (68 women; mean age, 65.9 years) with stage 4 metastatic lung cancer who were actively undergoing treatment.
The cohort included patients with adenocarcinoma non-small cell lung cancer (n = 79; 71.8%), small cell lung cancer (n = 18; 16.5%), squamous cell carcinoma (n = 7; 6.4%), and unspecified disease type (n = 5; 4.6%).
Treatments included chemotherapy (n = 47; 45.2%), immunotherapy (n = 35; 33.7%) and targeted therapy (n = 22; 21.2%).
CRP analysis showed an average concentration among the cohort of 1.79 mg/mL (median, 0.75 mg/mL; standard deviation [SD], 2.5 mg/mL), with 20.7% having levels of 3 mg/mL or higher.
A survey evaluated depression severity among study participants using the Hospital Anxiety and Depression Scale (HADS).
Twenty-six (23.9%) patients had clinically significant symptoms of depression (HADS 8) and 18 (16.5%) were taking antidepressant medication.
Results showed significant associations between depression and CRP (P < .001), receipt of chemotherapy (P = .006) and small cell lung cancer(P = .021).
Multiple regression analysis with these variables found that only log-transformed CRP was significantly associated with depression (adjusted R2 = 0.23; P = .001).
Linear regression showed CRP was a predictor for about 20% of depression variability (adjusted R2 = 0.2; P = .001).
Patients with significant depression scores had higher CRP levels than patients without high scores (3.4 mg/mL vs. 1.3 mg/mL; P = .003) and were more likely to be receiving advanced-line treatment.
CRP values had moderate predictive accuracy in identifying elevated depression (area under the curve = 0.74; P < .001). A CRP cutoff of 3 mg/mL or greater yielded 88% specificity but identified only half of those with elevated depression.
“Although studies have begun to evaluate the efficacy of using an easily obtained biomarker such as CRP to select antidepressant treatment, further studies are needed, and lung cancer may provide a unique setting that enhances for both inflammation and depression,” McFarland and colleagues wrote. “The appropriate selection of effective antidepressant medication or therapy in the inflamed, depressed lung cancer setting would reduce the overall burden of depression in [patients with] lung cancer.” – by John DeRosier
Disclosures: This study was funded by the NCI. McFarland The authors report no relevant financial disclosures.