Uncovering the Rare: A Systematic Review and Patient-level Meta-analysis of Testicular Metastases From Renal Cell...

To conduct the largest and most comprehensive individual patient data (IPD) meta-analysis to date on testicular metastases from renal cell carcinoma (RCC), with the aim of characterizing clinical features, quantifying survival outcomes, and identifying predictors of recurrence and mortality.

A systematic review was performed in April 2025 using PubMed, Scopus, Web of Science, and Google Scholar. Eligible studies included histologically confirmed testicular metastases from RCC with extractable patient-level data. Fifty-three cases from 40 articles were included. One unpublished case from our institution was included. We extracted demographics, pathology, treatment, imaging, and outcome data. Tumor volume was calculated from ultrasound dimensions using the ellipsoid formula. For bilateral metastases, the mean volume was used in regression analysis.

The median overall survival was 17 months (interquartile ranges [IQR], 7.4-26), and progression-free survival was 9 months (IQR, 6-18.5). Lymph node metastasis (odds ratio [OR] = 15.7, P = .019) and presence of metastases at RCC diagnosis (OR = 6.5, P = .034) were associated with mortality. Synchronous metastases (OR = 38.5, P = .002) and lung involvement (OR = 28.0, P = .004) were predictors of recurrence. Survival differed significantly across Fuhrman grades (P = .032) and T stages (P = .047). In Cox regression, metastasis at diagnosis predicted shorter overall survival, while lung and lymph node involvement were the strongest predictors of recurrence.

This meta-analysis provides the first pooled survival estimates and prognostic modeling for testicular RCC metastases. Findings support the value of early detection and confirm the prognostic impact of synchronous disease and nodal spread. These results establish a foundation for clinical risk stratification and long-term surveillance strategies in affected patients.