Comparative suicide risk in hematologic versus solid organ malignancies: A SEER-based competing-risks and cause-specific analysis of 7.4 million reports

Abstract

Abstract Background: Suicide remains a devastating and under-recognized outcome among cancer patients. While elevated suicide rates have been documented in various solid tumors, such as pancreatic and head and neck cancers, population-based comparisons with hematologic malignancies are lacking. Given the differing clinical trajectories, care settings, and survivorship experiences of patients with leukemia, lymphoma, and myeloma, understanding how suicide risk compares across cancer types is vital for tailoring prevention strategies. Methods: We analyzed 7,449,912 adult first-primary malignant cancer cases from the SEER 17 Registries (2000–2022). After excluding autopsy-only and death-certificate-only cases, tumors were classified as hematologic (leukemia, lymphoma, myeloma) or solid based on ICD-O-3 codes. Suicide was identified from SEER cause-of-death recodes. We calculated follow-up in months and modeled suicide risk using Fine–Gray subdistribution hazards (sdHRs) to account for competing mortality, alongside cause-specific Cox models (HRs) treating non-suicide deaths as censoring. Models adjusted for age (in 5-year bands), race/ethnicity, summary stage, rural–urbanstatus, county-level income quartile, and marital status. Effect modification was assessed via stratified models. Results: Hematologic cancers were associated with a 29% lower cumulative suicide risk than solid tumors (sdHR 0.71) and a similarly reduced instantaneous hazard (HR 0.71, p < 0.001). Among distant-stage patients, the difference was more pronounced (sdHR and HR 0.68, both p < 0.001). In income-stratified analysis, patients in the second-lowest income quartile experienced a 56% lower suicide hazard with hematologic versus solid tumors (HR 0.44, p < 0.001). Married patients with hematologic malignancies had a 28% lower suicide hazard (HR 0.72, p = 0.011), supporting the role of spousal support. Among Non-Hispanic White patients, hematologic cancers conferred a 29% lower suicide hazard (HR 0.71, p = 0.0013); Hispanic patients showed a 55% reduction that approached significance. Subgroups with sparse events (e.g., regional-stage hematologic cases, separated individuals, and certain minority groups) yielded unstable estimates due to low suicide counts. Conclusion: In this population-based study of over 7.4 million cancer patients, hematologic malignancies showed consistently lower suicide risk than solid tumors across clinical and demographic subgroups. This association was strongest in distant-stage disease, middle-income groups, and married individuals. Potential explanations include more continuous outpatient care, integrated psychosocial support, fewer disfiguring surgeries, and greater curative potential in some hematologic subtypes, all of which may reduce psychological distress. These findings support prioritizing suicide-prevention efforts for high-risk solid-tumor patients, particularly those facing advanced disease, financial hardship, or limited support networks. Embedding mental-health screening into routine oncology care and tailoring interventions by cancer type may help mitigate this preventable harm.