Time-Updated TNM Stage and Risk of Clinician-Documented Suicidal Ideation After Cancer Diagnosis: A Hospital-Based Cohort Study

Purpose: Suicide risk is elevated among patients with cancer, but how clinician-documented suicidal ideation varies across time-updated TNM stages remains unclear. We examined this association after cancer diagnosis. Materials and Methods: We conducted a retrospective cohort study of 134,369 patients using tumor registry and clinical records from Yonsei Cancer Center covering 2005-2021. We identified clinician-documented suicidal ideation using rule-based keyword screening and manual contextual review of electronic medical records. TNM stage was classified as CIS or stages I-IV and updated across eligible intervals. We estimated hazard ratios (HRs) using a marginal structural Cox model (MSM). Results: During follow-up, clinician-documented suicidal ideation was recorded in 6,718 patients (5.0%). Compared with TNM stage I, adjusted HRs were 0.81 (95% CI, 0.61-1.07) for CIS, 1.36 (1.25-1.49) for stage II, 1.20 (1.11-1.31) for stage III, and 1.54 (1.43-1.67) for stage IV. The stage III estimate was lower than the stage II estimate. Conclusion: Time-updated TNM stage was associated with clinician-documented suicidal ideation after cancer diagnosis, with the highest adjusted hazard observed for stage IV. These findings highlight the relevance of cancer-stage information to psychosocial assessment in cancer care.