Abstract
IMPORTANCE: Patients with head and neck cancer experience high rates of depression. Depression and systemic inflammation have been found to be associated in numerous cancer types, often independently from disease status. Depression-related inflammation may elevate the risks for poor tumor response to treatment and early mortality, and comprises a mechanism by which depression is associated with survival in head and neck cancer. OBJECTIVE: To assess mediation pathways incorporating pretreatment depressive symptoms, pretreatment inflammation, and tumor response posttreatment on overall survival among patients with head and neck cancer. DESIGN, SETTING, AND PARTICIPANTS: This was a prospective observational cohort study of patients with head and neck cancer treated in a single multidisciplinary head and neck cancer clinic from May 10, 2013, to December 30, 2019, and followed up for 2 years. Data analysis was performed from June 29, 2022, to June 23, 2023. EXPOSURES: Patient-reported depressive symptoms using the Patient Health Questionnaire-9 item (PHQ-9) at treatment planning; pretreatment hematology workup for systemic inflammation index (SII) score; and clinical data review for tumor response (complete vs incomplete) and overall survival. MAIN OUTCOMES: Two-year overall survival. RESULTS: The total study cohort included 394 patients (mean [SD] age, 62.5 [11.5] years; 277 [70.3%] males) with head and neck cancer. Among 285 patients (72.3%) who scored below the clinical cutoff for depression on the PHQ-9, depressive symptoms were significantly associated with inflammation (partial r, 0.168; 95% CI, 0.007-0.038). In addition, both depression and inflammation were associated with early mortality (PHQ-9: hazard ratio [HR], 1.04; 95% CI, 1.02-1.07; SII: HR, 1.36; 95% CI, 1.08-1.71). The depression-survival association was fully mediated by inflammation (HR, 1.28; 95% CI, 1.00-1.64). Depressive symptoms were also associated with poorer tumor response (odds ratio, 1.05; 95% CI, 1.01-1.08), and the depression-survival association was partially mediated by tumor response (HR, 9.44; 95% CI, 6.23-14.32). Systemic inflammation was not associated with tumor response. CONCLUSIONS: In this cohort study, systemic inflammation emerged as a novel candidate mechanism of the association of depression with mortality. Tumor response partially mediated effects of depression on mortality, replicating prior work. Thus, depression stands out as a highly feasible target for renewed clinical attention. Even mild symptoms of depression during the treatment-planning phase may be associated with higher systemic inflammation in addition to poorer tumor response to treatment and survival outcomes; therefore, depression should be clinically addressed.