Prognostic Significance of Organ-Specific Metastases in Patients with Metastatic Upper Tract Urothelial Carcinoma

Background: Existing data on metastatic upper tract urothelial carcinoma (mUTUC) are limited. In this study, we investigated the prognostic value of site-specific metastases in patients with mUTUC and its association with survival outcomes. Methods: We retrospectively collected data from the Surveillance, Epidemiology and End Results (SEER) database between 2004 and 2016. Kaplan-Meier analysis with a log-rank test was used for survival comparisons. Multivariate Cox regression was employed to predict overall survival (OS) and cancer-specific survival (CSS). Results: 633 patients were selected in this study cohort. The median follow-up was 6 months (IQR 2-13) and a total of 584 (92.3%) deaths were recorded. Within the population presenting with a single metastatic organ site, the most common metastatic sites were distant lymph nodes, accounting for 36%, followed by lung, bone and liver metastases, accounting for 26%, 22.8% and 16.2%, respectively. In patients with a single metastatic organ site, the Kaplan-Meier curves showed significantly worse OS for patients with liver metastases vs. patients presenting with metastases in a distant lymph node (p < 0.001), bone (p = 0.023) or lung (p = 0.026). When analyzing CSS, statistically significant differences were detectable only between patients presenting with liver metastases vs. distant lymph node metastases (p < 0.001). Multivariate analyses showed that the presence of liver (OS: HR = 1.732, 95% CI = 1.234-2.430, p < 0.001; CSS: HR = 1.531, 95% CI = 1.062-2.207, p = 0.022) or multiple metastatic organ sites (OS: HR = 1.425, 95% CI = 1.159-1.753, p < 0.001; CSS: HR = 1.417, 95% CI = 1.141-1.760, p = 0.002) was an independent predictor of poor survival. Additionally, survival benefits were found in patients undergoing radical nephroureterectomy (RNU) (OS: HR = 0.675, 95% CI = 0.514-0.886, p = 0.005; CSS: HR = 0.671, 95% CI = 0.505-0.891, p = 0.006) and chemotherapy (CHT) (OS: HR = 0.405, 95% CI = 0.313-0.523, p < 0.001; CSS: HR = 0.435, 95% CI = 0.333-0.570, p < 0.001). Conclusions: A distant lymph node was the most common site of single-organ metastases for mUTUC. Patients with liver metastases and patients with multiple organ metastases exhibited worse survival outcomes. Lastly, CHT administration and RNU were revealed to be predictors of better survival outcomes in the mUTUC cohort.