Small cell prostate cancer: risks for metastatic disease.

Objective: To identify clinical and demographic factors associated with the presence and distribution of metastatic disease at diagnosis in patients with small cell carcinoma of the prostate (SCCP). Introduction: Small cell carcinoma of the prostate is a rare but highly aggressive subtype of prostate cancer, frequently presenting with distant metastases and poor survival outcomes. Despite its severity, population-level data examining predictors of metastatic disease at presentation remain limited. Understanding these factors may improve early detection and risk stratification. Methods: A retrospective, cross-sectional analysis was conducted using the SEER 17 registries (2000-2022). Patients with microscopically confirmed SCCP were identified using ICD-O-3 histology code 8041/3 and primary site code C61.9. Demographic, clinical, and metastatic variables were extracted. Univariate and multivariable logistic regression models were used to evaluate predictors of overall and site-specific metastases. Variables meeting a univariate threshold of p < 0.25 were included in multivariable models. Model assumptions were assessed using VIF, Tolerance, and Box-Tidwell tests. Results: A total of 541 patients were identified, of whom 71.7% presented with metastatic disease. The most common metastatic sites were bone (35.9%), liver (22.6%), lung (14.0%), and brain (3.9%). On multivariate analysis, a higher percentage of positive biopsy cores was independently associated with increased odds of metastatic disease. Younger age was associated with higher odds of brain metastasis. Lower household income and residence in metropolitan counties were associated with increased likelihood of metastatic disease, particularly bone metastases. Brain metastasis was strongly associated with concurrent liver and lung metastases, suggesting a pattern of widespread systemic involvement. Conclusions/discussion: Patients with SCCP frequently present with metastatic disease, and several clinical and socioeconomic factors influence metastatic risk. Higher tumor burden, lower income, metropolitan residence, and younger age were associated with a greater likelihood of metastasis at diagnosis. These findings highlight the importance of early diagnostic evaluation in high-risk groups and provide a foundation for improved prognostication and targeted care strategies in this rare and aggressive malignancy.