Clinical Outcomes and Clinicopathological Features of Primary Urethral Carcinoma: A Multicenter Retrospective Study in Japan

OBJECTIVES: Primary urethral carcinoma is an extremely rare malignancy, and evidence on its treatment and prognosis remains limited. This study aimed to clarify the treatment patterns, clinical outcomes, and prognostic factors for primary urethral carcinoma in Japan. METHODS: This retrospective study across 10 institutions included 57 Primary urethral carcinoma cases between 2004 and 2022. Recurrence-free survival and overall survival were estimated using the Kaplan-Meier method, and overall survival-related factors were evaluated using univariate Cox regression analysis. RESULTS: The cohort comprised 24 men (42%) and 33 women (58%), with a median tumor size of 30 mm (interquartile range, 15-48 mm). Stage distribution was ≤ I in 17 (30%), II in 10 (18%), III in 8 (14%), and IV in 21 (38%) patients. Urothelial carcinoma, including cases with divergent differentiation, was the predominant histological subtype, identified in 17 men (71%) and 14 women (42%). The median follow-up time was 17.1 months (interquartile range, 6.4-37.7 months). Overall survival did not differ significantly between Stage I and Stage II disease (p = 0.499), whereas it was significantly shorter in patients with Stage III and Stage IV disease compared with Stage I (p = 0.030 and p < 0.001, respectively). Previous urinary catheter placement, urethral diverticulum, and elevated lactate dehydrogenase (> 220 IU/L) were significantly associated with poorer overall survival. CONCLUSIONS: Stage ≤ II Primary urethral carcinoma has favorable survival following definitive treatment, Stage III-IV disease showed poor outcomes, necessitating multimodal perioperative strategies (chemotherapy and/or radiotherapy).