Tumor Mutation Burden and Depression in Lung Cancer: Association With Inflammation

Background: Patients with lung cancer with greater systemic inflammation have higher rates of depression. Tumor mutation burden (TMB) predicts immunotherapy response in patients with lung cancer and is associated with intratumoral inflammation, which may contribute to systemic inflammation and depression. This study evaluated whether higher TMB was associated with increased depression and systemic inflammation in patients with lung cancer. Patients and Methods: Patients with metastatic lung cancers were evaluated for depression severity using the Hospital Anxiety and Depression Scale. TMB was measured using the Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets. Inflammation was evaluated using C-reactive protein (CRP) level and neutrophil-to-lymphocyte ratio (NLR). Results: A total of 96 patients with adequate TMB testing were evaluated. The average number of mutations (TMB) was 10.8 (SD, 10.9). A total of 19% of patients endorsed clinically significant depression symptoms. TMB was significantly correlated with depression severity (r=0.34; P=.001) and NLR (r=0.37; P=.002) but not CRP level (r=0.19; P=.07). TMB was also higher in patients receiving chemotherapy (mean, 12.0) and immunotherapy (mean, 14.4) versus targeted therapy (mean, 4.8). A multivariate model found that TMB (beta=0.30; P=.01) and CRP level (beta=0.31; P=.01) were independently associated with depression; there was no significant interaction effect of TMB 3 CRP and depression. A similar multivariate model showed no independent effect for NLR and depression (beta=0.16; P=.17) after accounting for TMB. Conclusions: These data provide evidence for biologic depression risk in patients with lung cancer who have high levels of TMB. The underlying mechanism of the association is not clearly related to inflammation but warrants further analysis to broadly elucidate the mechanism of biologically derived depression in cancer.