Impact of Metastatic Pattern on Survival in Patients with Posterior Uveal Melanoma: A Retrospective Cohort Study

Background/Objectives: Metastatic posterior uveal melanoma (PUM) is one of the deadliest types of melanomas. Though the median survival is short, some patients with metastatic disease live for a long time. In this study, we investigated whether the anatomical location of the metastatic lesions is associated with differences in survival. Methods: One hundred and seventy-eight patients with metastatic PUM with baseline whole-body imaging were retrospectively included. The patients were divided into three groups based on the anatomical location of metastases: (1) exclusive liver metastases (hepatic pattern), (2) both hepatic and extrahepatic metastatic lesions (hepatic-extrahepatic pattern), and (3) exclusive extrahepatic lesions (extrahepatic pattern). Survival was investigated using Kaplan-Meier plots, log-rank test, and the Cox proportional hazard model. Results: In total, 95 patients (53%) presented with hepatic pattern, 66 patients (37%) presented with hepatic-extrahepatic pattern, and 17 patients (10%) presented with extrahepatic pattern. Overall survival was significantly longer in patients with extrahepatic pattern (median 17.0 months) compared to those with hepatic pattern (median 11.0 months) and hepatic-extrahepatic pattern (median 7.0 months) (p < 0.001, log-rank test). Multivariate Cox regression analysis showed increased hazard ratios (HR) for hepatic pattern (HR 2.37, 95% CI 1.08-5.17, p = 0.031) and hepatic-extrahepatic pattern (3.25, 95% CI 1.42-7.41, p = 0.005) compared to extrahepatic pattern. Most patients with hepatic (95%) and hepatic-extrahepatic patterns (82%) were diagnosed with metastases by liver ultrasonography screening, whereas 81% of patients with extrahepatic pattern developed symptoms that led to the diagnosis. Conclusions: Extrahepatic pattern was associated with prolonged survival in patients with metastatic PUM, despite there being a larger proportion of symptomatic patients. It is therefore important to consider the anatomical location of the metastatic lesions when stratifying patients into clinical trials.