Prognostic impact of brain metastases on survival rates in patients with metastatic testicular cancer: A comprehensive registry-based analysis.

5023 Background: Testicular cancer (TC) is a rare malignancy that accounts for less than 1% of all cancers. Advances in the treatment paradigm have improved survival rates. However, oncologic outcomes may vary based on the extent and location of metastasis. Brain metastases (BM) are rare but may lead to worse survival outcomes. We aimed to conduct the largest retrospective study of patients with metastatic TC (mTC) to evaluate the prognostic impact of brain metastasis on survival rates in patients with IGCCC intermediate or poor risk mTC. Methods: We utilized the National Cancer Database (2010-2021) to identify patients with mTC(T1-4, any N0-2, M1). Patients with isolated lung metastases were excluded, as lung involvement alone was considered a surrogate marker for patients with good risk disease. We utilized Kaplan Meier analysis and cox proportional hazard modelling to study the impact of BM on survival outcomes in patients with mTC. Results: A total of 4,076 patients with mTC met our study criteria, of which 11.14% (454) had BM. Among these, 36.11% (1,472) had seminoma, 27.16% (1,107) had non-seminomatous histology, and 36.73% (1,497) had mixed germ cell tumors. The 2- and 5-year survival rates for patients without BM were 82.63% (95% CI: 81.26–83.91) and 78.26% (95% CI: 76.72–79.71), respectively. For patients with BM, the 2- and 5-year survival rates were 51.01% (95% CI: 45.99–55.79) and 42.78% (95% CI: 37.72–47.72), respectively. In our adjusted analysis, patients with BM had 2.35-fold increased risk of death (HR: 2.35, 95% CI: 1.96–2.82, p<0.001), compared to those without BM. Additionally, compared to seminoma, non-seminomatous histology had a 1.72-fold increased hazard of death (HR: 1.72, 95% CI: 1.42–2.09, p<0.001), while mixed germ cell tumors had a 1.34-fold increased hazard of death (HR: 1.34, 95% CI: 1.10–1.62, p = 0.003). Conclusions: In this large-scale retrospective cohort study, patients with BM had 135% increased risk of death in patients with mTC compared to patients without BM. Additionally, non-seminomatous and mixed germ cell histology were associated with significantly worse outcomes compared to seminoma. These findings highlight the importance of aggressive, tailored treatment strategies to address the higher mortality risk posed by BM in patients with intermediate and poor risk metastatic testicular cancer. Cox proportional hazard model in patients with mTC. Variable HR (95% CI) P-value Histology: Seminoma Ref Non seminoma 1.72 (1.42–2.09) < 0.001 Mixed germ cell 1.34 (1.10–1.62) 0.003 Brain Metastasis: No Ref YES 2.35 (1.96–2.82) < 0.001 Bone Metastasis No Ref YES 1.43 (1.20–1.71) < 0.001 Liver Metastasis: No Ref YES 1.65 (1.40–1.96) < 0.001