Financial toxicity and quality of life in advanced lung cancer: The role of depressive symptoms.

e24110 Background: Financial toxicity (FT) is a critical burden in individuals with advanced lung cancer and is strongly associated with impaired health-related quality of life (HRQoL). However, the psychological mechanisms driving this association remain insufficiently understood. Methods: This cross-sectional study enrolled 251 patients with advanced lung cancer in Taiwan. FT was assessed using the FACIT-COST (↑ scores indicate ↓ FT). Depressive symptoms were assessed using PHQ-9. General and lung cancer-specific HRQoL, were assessed using the EORTC QLQ-C30 and QLQ-LC29, respectively. Causal mediation analysis with 1,000 bootstrap resamples was employed to estimate the average causal mediation effect (ACME) and average direct effect (ADE). Results: The mean COST score was 25.8±10.1, with 41.8% of participants experiencing moderate-to-severe FT. Lower COST scores (↑ FT) were significantly associated with ↑ depressive symptom severity (r = −0.47, p < .001) and poorer global HRQoL (r = 0.34, p < .001). Among QoL domains, social functioning was the most severely impaired, alongside lung cancer-specific stressors such as fear of progression and future health concerns. Causal mediation analysis revealed that depressive symptoms significantly mediated the relationship between FT and HRQoL (ACME = 0.33, 95% CI: 0.00–0.69; p = .050). Notably, the direct effect of FT on HRQoL was not statistically significant (ADE = 0.12; p = .62), suggesting that depressive symptoms mediate this association. Conclusions: Depressive symptoms appear to play a central role in linking FT to impaired HRQoL among patients with advanced lung cancer. These findings suggest that mitigating the psychological sequelae of financial burden may be as critical as providing direct financial assistance. Integrating psychosocial screening and targeted mental health support into supportive care strategies may help alleviate the clinical impact of FT and improve patient-centered outcomes.