Suicide, defined as the deliberate act of ending one’s own life, represents a significant issue concern in global public health. In the United States, suicide ranked as the 11^th leading cause of death in 2021. The age-adjusted suicide rate witnessed an upward trajectory from 2001 (10.7 deaths per 100,000 standard population) to 2018 (14.2 deaths per 100,000 standard population). Subsequently, it declined for two consecutive years, reaching 13.5 deaths per 100,000 standard population in 2020, before rising again to 14.1 deaths per 100,000 standard population in 2021 (1). Cancer is the second leading cause of mortality in the United States, with an estimated 1,898,160 new cancer diagnoses and approximately 608,570 deaths attributed to cancer in the year 2021 (2). Although suicide accounts for merely 0.154% of deaths among cancer patients, the risk of suicide in this group was 4.4 times higher than that of the general population (3). Cancer can affect the immune system, potentially leading to depression and suicidal ideation, which in turn might trigger suicide (4). The risk factors for suicide in cancer patients encompass sociodemographic factors (age, gender, marital status and race), psychiatric disorders (pre-existing psychopathology, depression, anxiety and others), psychosocial factors (poor social support and loss of independence, feeling of being a burden), medical factors (advanced disease and poor prognosis and others), previous suicide attempt and suicidal thoughts (4). Studies have delved into the identification of pertinent risk factors for specific types of cancer and have consequently formulated predictive models tailored to these conditions, such as those for lymphoma (5), bladder cancer (6) and lung cancer (7).

Leukemia was the 15^th most commonly diagnosed cancer in 2018 and the 11^th leading cause of cancer-related deaths globally. There was a 25% increase in the total number of leukemia cases from 2005 to 2015 (8). Patients diagnosed with leukemia face an elevated risk of suicide for up to two years post-diagnosis. This heightened risk is attributed to the fact that many individuals transitioning to survivorship care endure long-term and late effects, both in physical and psychological, functional impairments, and poor quality of life (9). Identifying factors associated with the risk of suicide among leukemia patients is crucial. It enables early intervention by psychiatrists and has the potential to lower the rate of suicide. Although previous research have examined risk factors for suicide in leukemia patients (10, 11), no predictive model has yet been developed to quantify the individual suicide risk for this specific population.

In this study, we leveraged leukemia data from the SEER database to construct a predictive nomogram, which is designed to quantify the risk of suicide subsequent to a leukemia diagnosis among patients. We hope to assist clinicians in identifying those leukemia patients at high suicide risk during the process of diagnosis and treatment to reduce the unnecessary deaths of patients.

A cancer diagnosis often leads patients to endure significant distress and exhibit psychiatric symptoms, thereby indicating an elevated risk of suicide (16). Leukemia, a prevalent malignancy affecting the hematologic system, exhibits a suicide rate that surpasses that of the general population, with a standardized mortality ratio (SMR) of 2.16 (11). In our study, based on the SEER database, through univariate Cox regression and multivariate Cox regression, we finally screened six factors including age, gender, race, residence, marital status and histologic type, affecting suicide among leukemia patients. Subsequently, we constructed a Nomogram. The C-index and time-dependent ROC curves demonstrated outstanding discrimination capabilities, while the calibration curves confirmed a high degree of agreement between the predicted and observed survival probabilities. Diverging from previous studies that focused solely on risk factors identification, our predictive model assigns a quantifiable suicide risk score for each patient. To the best of our knowledge, this was the first predictive model specifically designed to quantify suicide risk in leukemia patients. This innovative approach allows hematologists to more accurately identify individuals at increased risk for suicide during clinical consultations, allowing for early intervention.

Males are generally at a significantly higher risk of suicide compared to females. This assertion is supported by previous analyses of risk factors for suicide across various cancer types, as well as specific findings related to leukemia patients (10, 11, 17). During the period from 2001 to 2021, the suicide rate among males in the United States was reported to be three to four and a half times higher than that of females (1). Our findings align with this trend, revealing that the suicide risk among males is 7.05 times higher than females. This disparity may stem from the higher prevalence of aggression and alcoholism are more prevalent among males, both of which have been identified as strong precipitating factors for suicide, as supported by high-quality evidence (4, 18). Analysis of data from the National Violent Death Reporting System in the United States reveals that approximately one in five suicides is attributable to alcohol use. In 2021, the proportion of male suicides attributed to alcohol-associated factors (AAF) was significantly higher at 20.2% compared to 17.8% among females (P <.001) (19). Additionally, smokers demonstrated higher suicide-related risks than non-smokers (20), which may further contribute to the increased suicide risk observed in males. In the context of AML, males are more often categorized into the adverse-risk group according to European LeukemiaNet criteria. However, when comparing SF3B1 mutations, which are male-specific adverse outcome prognosticators, to SF3B1 mutations carried by females, males with these mutations have worse OS outcomes (21), This worse disease prognosis may suggest a higher suicide risk among these patients (5).

Among marital status categories, married patients have a lower risk of suicide compared to those who are single (HR: 1.44) and those belonging to other marital status groups (HR: 2.41), including unmarried or in domestic partnerships, separated, widowed, and divorced. Chen et al. discovered that suicide rates increased over time among individuals who were divorced/separated, never-married, or widowed, and that being married served as a protective factor against suicide risk (22). This finding was consistent with the results of our study. The influence of marital status on suicide rates was consistent and stable, and the reason of this relationship may be linked to the bonds of social support. Social support has been recognized as an environmental risk factor for suicide, and the lack of it among unmarried or divorced individuals may contribute to their increased suicide risk (18). Furthermore, for separated men, factors such as lower educational attainment, shame associated with separation, and stress from legal negotiations, particularly regarding property/financial issues, have been linked to the development of serious suicidal ideation (23).

White people had the highest risk of suicide with reports indicating that the suicide rate for white people was 13 per 100,000 person-years (24). In our study, being white people was identified as a risk factor when compared to Black, Hispanic, Asian or Pacific Islander and American Indian/Alaska Native papulations. Differences may be explained by variations in psychiatric disorders and lower risk factors prior to arriving in the United States, as many Hispanic and Asian individuals are immigrants (25). It is currently believed that Black people have higher levels of religious belief and family cohesion, which serve as protective factors against suicide risk. Furthermore, suicides among Black people are more likely to be misclassified as accidents or undetermined, potentially underestimating the suicide rate within this population (26).

Among patients diagnosed with leukemia, those with AML demonstrated the highest suicide risk, despite lymphocytic leukemia constituting the majority of the study population. AML is the most common type of leukemia in adults, particularly affecting older patients more severely than their younger counterparts, featured by rapid progression and poor prognosis. In our investigation, the proportion of individuals who died within 6 months was significantly higher in the AML group (47.2%) compared to lymphocytic leukemia group (10.3%). A poor prognosis was strongly correlated with suicide risk in the initial stages following a cancer diagnosis (27). Additionally, secondary leukemia, which accounted for 40% of all AML or myelodysplastic syndrome (MDS) cases (28), may also contribute to this heightened risk. Patients with a history of prior tumors or other medical conditions who have undergone treatment are understandably at a higher risk of suicide than those with primary leukemia. Moreover, for patients who had antecedent hematologic conditions tend to exhibited poorer outcome than those with de novo AML.

It is noteworthy that older adults, particularly men over the age of 80, are at a higher risk of suicide compared to other age groups (29), a trend corroborated by both our study and previous research (30). This increased susceptibility can be attributed to various factors, including the loss of loved ones, loneliness, and the accumulation of physical illnesses that often accompany advancing age (29). Mood disorders, especially major depression, are prevalent among older adults who die by suicide, with estimates ranging from 54% to 87% (31) In the context of cancer patients, the prevalence of depression was even more pronounced, being four times higher than that of the general population, and is associated with adverse outcomes such as reduced adherence to treatment and increased mortality within the oncology setting (31). Among elderly, a significant number are unemployed (32), may also contribute to the increased risk of suicide in this population. Of note, though the population under 18 years old exhibited the lowest suicide risk in our study, there is a concerning global trend of increasing suicide risk within this demographic. Consequently, it is imperative to prioritize the mental health of children diagnosed with leukemia.

The geographic residence of leukemia patients emerged as a significant factor influencing their risk of suicide in our study. This phenomenon may be attributed to the poor mental health functioning observed among cancer survivors residing in rural areas, who exhibit heightened symptoms of anxiety, and depression, greater distress and more emotional problems compared to their counterparts in non-rural settings (33). Furthermore, individuals in rural locations often face limited access to mental health resources. However, it is important to note that residency is not static, due to the limitations of the SEER database, this study was unable to assess the impact of population mobility and geographical changes on the suicide risk among leukemia patients.

Although the nomogram developed in this study demonstrated strong performance, we acknowledge several limitations. Firstly, the SEER database does not provide information regarding hematopoietic stem cell transplantation (HSCT) for leukemia patients, while the significant role HSCT plays in the treatment process of leukemia. The elevated suicide rates in patients undergoing autologous HSCT have been associated with a higher rate of relapse, whereas the increased suicide rates in those receiving allogeneic HSCT were more attributable to chronic graft-versus-host disease (34). Additionally, patients who have undergone HSCT may be at risk for major depression (35). Secondly, The SEER database does not encompass information on drug use, psychiatric comorbidities, environmental exposures, and occupational background—factors that are widely acknowledged for their contribution to suicide risk. Consequently, these elements could not be integrated into our nomogram. Lastly, although we have established and validated our model within a large cohort, we have not conducted external validation of the model. The SEER data only contains data for Americans, so external validation in other countries and populations is necessary to verify generalizability and credibility. Traditionally, doctors assess a patient’s risk of suicide through interviews, which is a subjective method. Our model offers a specific scoring system for leukemia patients to quantify their risk of suicide. Regular screening for suicide risk is essential, and those identified as being at high risk should be promptly referred to a psychiatrist for treatment. Additionally, communication with patients and their families is crucial to understand any changes in the patient’s physical and psychological state.

Suicide represents a significant global public health concern, resulting in numerous fatalities worldwide. Notably, its incidence among individuals with cancer is higher compared to the general populace. Utilizing the SEER database, we employed the Cox proportional hazards model to pinpoint six factors—namely, age, gender, race, residence, histological type, and marital status—that are linked to suicidality among leukemia patients. Consequently, we formulated a straightforward yet reliable model that aids specialists in promptly identifying individuals at heightened risk of suicide, thereby enabling them to enhance the patients’ prognosis.