Primary malignancies of the epididymis: clinical characteristics and prognostic factors.

INTRODUCTION We sought to describe clinical characteristics and identify prognostic factors among patients with primary malignancies of the epididymis (PMEs).
Materials and Methods: The Surveillance, Epidemiology, and End Results (SEER) database (1975-2015) was queried to identify patients with PME. Descriptive statistics and multivariable Cox proportional hazards models were used.
Results: Eighty-nine patients with PME were identified. Median age was 57 years (5-85), and median overall survival (OS) was 16.8 years. The most commonly represented histologies were rhabdomyosarcoma (19.1%), B-cell lymphoma (16.9%), leiomyosarcoma (16.9%), and liposarcoma (12.4%). In multivariable analysis, tumor size ≥ 4 cm was associated with worse OS (HR = 4.46, p = 0.01) compared to tumors < 4 cm. Patients with nonsarcomatoid histology had OS similar to patients with sarcomatoid histology (HR = 0.95, p = 0.92). Disease with regional invasion (HR = 5.19, p = 0.007) and distant metastasis (HR = 29.80, p = 0.0002) had worse OS compared to localized disease. Receipt of radiotherapy was associated with enhanced OS (HR = 0.10, p = 0.006), whereas receipt of chemotherapy was not associated with OS.
Conclusions: We describe the largest cohort of PMEs to date. Larger lesions and tumor stage were independently associated with poor overall survival, while receipt of radiotherapy was associated with enhanced overall survival.