Depression, performance status, and discontinued treatment mediate an association of curability belief with prognosis in advanced cancer patients.

Individuals diagnosed with advanced cancer often experience stress and depression, factors linked to worse survival. Curability belief-defined as the hope and expectation of cure through treatment, based on affective forecasting-may differ from the patient's actual life expectancy (i.e., likelihood estimation) and has shown variable associations with cancer survival. In this study, multivariate Cox regression analyses were used to examine the effect of curability belief and depression on 1-year survival after adjustment for physical factors. Additionally, regularized partial correlations among physical and psychological factors were assessed using mixed graphical models to elucidate their roles in mediating the relationship between curability belief and 1-year survival. This multi-center cohort study, conducted across 13 tertiary hospitals (including four ranked among the 'World's Best Specialized Hospitals 2025' in oncology), involved 382 adults with stage IV advanced cancer and an oncologist-estimated survival of more than 6 months. Baseline data included demographics, primary tumor site, number of metastatic sites, symptom burdens (EORTC QLQ-C15-PAL), performance status (ECOG-PS), depression levels (PHQ-9), anti-cancer treatment type, patient's life expectancy estimation, and curability belief. Follow-up data included 1-year survival and end-of-life care (place of death) for deceased patients. Multivariate Cox proportional hazards models were used to assess adjusted hazard ratios (aHRs) for curability belief, depression, and their interaction on 1-year survival, adjusting for significant demographic and clinical factors from univariate Cox regressions. The Kaplan-Meier method was used to plot survival probability by curability belief and depression interaction. Mixed graphical models estimated regularized partial correlations among 1-year survival, curability belief, patient's life expectancy, depression, primary tumor site, anti-cancer treatment type, performance status, and symptom burden. In terms of healthcare utilization, patients with curability belief were more likely to receive standard or advanced anti-cancer therapy, while those without curability belief tended to suspend or discontinue therapy (P < 0.001). Among patients who did not survive the 1-year follow-up (N = 161), end-of-life care settings differed significantly between those with curability belief (predominantly nursing homes and home settings) and those without (primarily hospice and tertiary/secondary hospitals; P = 0.036). In multivariate Cox regression, curability belief (P = 0.003), depression (PHQ-9 score ≥ 10; P = 0.003), and their interaction (P = 0.040) were significantly associated with 1-year survival, after adjusting for sex, residential area, primary tumor site, performance status, anti-cancer treatment type, and symptom burdens (fatigue and appetite loss). The relationship between curability belief and 1-year survival was significant only in patients without depression [PHQ-9 score < 10; aHR (95% CI) = 2.20 (1.31-3.70); P = 0.003]. In the mixed graphical model, node predictability values for curability belief, depression, and 1-year survival were 0.68, 0.50, and 0.70, respectively, with curability belief showing partial correlations with depression (r = 0.30) and patients' life expectancy (r = 0.20); depression correlated with fatigue (r = 0.53), anorexia (r = 0.16), life expectancy (r = 0.24), performance status (r = 0.23), and curability belief; and 1-year survival correlated with suspended/stopped anti-cancer treatment (r = 0.45), primary tumor site (r = 0.24), and performance status (r = 0.15). Partial correlations of performance status with depression and discontinued treatment mediated the association between curability belief and 1-year survival. Curability belief among stage IV advanced cancer patients with an oncologist-estimated survival of over 6 months was associated with depression levels and patients' perceived life expectancy estimations. Performance status, depression, and anti-cancer treatment status mediate the relationship between curability belief and improved 1-year survival in patients without depression. Further research using longitudinal modeling of depression, performance status, and healthcare utilization, with curability belief and primary tumor site as covariates, is warranted.Trial registration: Clinical Trial Number (ClinicalTrials.gov): NCT03222258; Study Registration Dates (First submitted: 2017-06-05; First submitted following the QC criteria: 2017-07-16; First posted: 2017-07-19).