Suicide is a rare but catastrophic event that can occur during a patient’s cancer course. The adjusted suicide rate for patients with cancer is 31 per 100,000 person-years (65 in males and 12 in females), versus 16.7 in the general population. For men with prostate cancer, the rate of suicide is 41 per 100,000 person-years. Prostate cancer represents the largest burden of cancer-related suicides, accounting for 29% of cancer-related suicides in men and 25% overall. Eighty-five percent of prostate cancer-related suicides occur in men over 60 years. Additionally, the vast majority (79%) of cancer-related suicides occur late (after six months) in the patient’s cancer course. Virtually all studies have focused on early suicides in patients with cancer, likely due to limitations inherent to using large cancer registries.
Depression is the most common risk factor for suicide but has not been well-investigated as a risk factor for suicide in persons with cancer in the US. The stress-diathesis model in psychiatry predicts that significant life stressors, such as a cancer diagnosis, could trigger suicidal behavior in a person with a history of depression. Whether depression interacts with the stress of cancer diagnosis and treatment to increase the risk of suicide is unknown.
Androgen-deprivation therapy (ADT) is a standard therapy for patients with prostate cancer and is associated with increased rates of depression and depressive symptoms. Despite this, there are no rigorous studies exploring the association between hormonal therapy and suicide risk in men with prostate cancer. History of depression and ADT may synergize to increase the risk of suicide. Both depression and androgen deprivation cause dysfunction in the monoamine oxidase pathway, which can be targeted with selective serotonin or serotonin-norepinephrine reuptake inhibitors.
To address these knowledge gaps, we will examine suicide risk in elderly men with prostate cancer using the Surveillance, Epidemiology, and End Results (SEER)-Medicare database, which links the largest US cancer population-based and claims-based datasets, providing a unique opportunity for longitudinal study of patients with cancer in granular detail.
The specific aims are:
- To determine the early (<6 months) and late (>6 months) incidence rates of suicide in men (white vs black) newly diagnosed with prostate cancer in SEER-Medicare between 2000-2019. We will identify demographic and clinical risk factors that predict its occurrence (year of diagnosis, age, race, ethnicity, marital status, socioeconomic status, rural vs urban, comorbidities, stage, Gleason score, radiotherapy vs surgery).
- To determine the association of psychiatric comorbidities with the risk of early and late suicide (depression, bipolar disorder, substance use disorder).
- To determine the association of treatment with ADT with risk of suicide.
This knowledge will lead to future interventions to prevent suicide in men with prostate cancer.
