To examine the efficacy of the Single Suicide Question, a tactful single-item tool, in assessing suicide risk among cancer patients. Suicide risk screening in cancer patients faces challenges such as cultural, the degree of attention given and the complexity and diversity of assessment methods. An efficient and simple suicide screening tool is needed within the nursing and treatment process. A retrospective cross-sectional study. All data utilised in this study were obtained from assessments conducted by researchers at our institution between March 2018 and August 2023. Retrospectively analysed Single Suicide Question scores from 9703 patients (March 2018-August 2023), with 229 undergoing additional using other established tools (the Patient Health Questionnaire-9, Generalised Anxiety Disorder-7, Distress Thermometer) alongside the Mini International Neuropsychiatric Interview Suicidal Subscale (MINI Suicidal Subscale). These 229 patients were divided into the cut-off determination dataset (174/229) and the validation dataset (55/229) to analyse, validate and compare the screening efficacy, consistency and optimal cut-off points of the tools relative to the MINI Suicidal subscale (golden standard). K-fold cross-validation was employed to assess the stability of the Single Suicide Question and to revalidate its screening efficacy. In cut-off determination dataset, the Single Suicide Question exhibited good screening efficacy and substantial agreement relative to the MINI Suicidal subscale, as validated in the validation dataset, outperforming other tools. The optimal cut-off points of Single Suicide Question for screening moderate or higher and high suicide risk as 2 and 3 respectively. Its stability in K-fold cross-validation further supported its screening efficacy. The Single Suicide Question shows potential as a preliminary screening tool for suicide risk. Furthermore, it has also demonstrated the potential of a simple, tactful, culturally fitting question in assessing suicide risk, providing insight for the development of relevant tools in different cultural and linguistic backgrounds. Our study demonstrates the potential of the Single Suicide Question as a screening tool for identifying suicide risk among cancer patients, which may facilitate efficient suicide screening. Furthermore, it reveals that tactful, culturally fitting, yet simple tools can achieve good screening efficacy, providing insights for the development of similar tools in different cultural and linguistic contexts. This study investigated the effectiveness of using a culturally contextualised, specific single question to screen for suicide risk in Chinese cancer patients, demonstrating high screening efficacy and stability. With further research, this method may provide a tactful, culturally informed and efficient suicide screening approach to address the critical issue of suicide risk in cancer care, and it also serves as a reference for developing similar tools in diverse cultural and linguistic contexts. The study followed the STROBE checklist guidelines for cross-sectional studies. The data provided by patients were the foundation of this study. Nurses played a central role in conducting the majority of assessments and contributing to the research design in this study.