Analysis of suicide risk in adult US patients with squamous cell carcinoma: a retrospective study based on the Surveillance, Epidemiology and End Results database

OBJECTIVES: The purpose of this study was to determine the risk factors for suicide in patients with squamous cell carcinoma (SCC) in the USA. SETTING: Patients with SCC diagnosed between 1975 and 2017 from the Surveillance, Epidemiology and End Results (SEER) database were selected for this study. PARTICIPANTS: This study included patients with SCC older than 20 years who were diagnosed between 1975 and 2017. PRIMARY AND SECONDARY OUTCOME MEASURES: The general population included in data from the US Centers for Disease Control and Prevention were used to calculate the suicide rate and standardised mortality rate (SMR) of SCC patients. Univariate and multivariate Cox regression analyses were used to identify risk factors for suicide in patients with SCC. RESULTS: There were 415 268 SCC patients registered in the SEER database, among which 1157 cases of suicide were found, comprising a total of 2 289 772 person-years. The suicide rate for patients with SCC was 50.53 per 100 000 person-years, and the SMR was 4.13 (95% CI 3.90 to 4.38). The Cox regression analyses showed that the factors related to a high risk of suicide among patients with SCC included being male (vs female: HR 5.36, 95% CI 4.51 to 6.38, p<0.001), older at the diagnosis (70–79 vs ≤39 years: HR 1.46, 95% CI 1.09 to 2.08, p=0.012; ≥80 vs ≤39 years: HR 1.48, 95% CI 1.05 to 2.08, p=0.025) and white (vs black, HR 2.97, 95% CI 2.20 to 4.02, p<0.001) and surgery (vs not performed: HR 0.65, 95% CI 0.57 to 0.74, p<0.001). CONCLUSIONS: Compared with the general population, patients with SCC in the USA have a higher risk of suicide. Being male, older at the diagnosis, white and having a higher histological grade are risk factors for suicide in patients.