Urothelial Carcinoma With Squamous Differentiation Is Associated With High Tumor Stage and Pelvic Lymph-Node Metastasis.

BACKGROUND: Squamous differentiation occurs in up to 20% of urothelial carcinoma cases and is thought to be an unfavorable prognostic factor.

METHODS: Data from urothelial carcinoma in patients treated with cystectomy from 2002 to 2014 at Roswell Park Cancer Institute were retrospectively reviewed. A 2-tier system was adopted for stage analysis. T1 and T2 disease were grouped in organ-confined and low-stage categories, whereas T3 and T4 disease were grouped in high-stage categories. The extent of squamous differentiation was semi-quantified as focal (≤20%) or extensive (> 20%).

RESULTS: Squamous differentiation occurred in 19.3% (47 of 244) of cases. Urothelial carcinoma with squamous differentiation presented with a significantly higher rate of high-stage disease compared with pure urothelial carcinoma (72.3% vs 43.1%; P < .01). The nodal metastatic rate in urothelial carcinoma with extensive squamous differentiation was significantly higher than that seen in pure urothelial carcinoma (46.2% vs 27.0%; P = .04).

CONCLUSIONS: Urothelial carcinoma with squamous differentiation is associated with advanced tumor stage. In addition, urothelial carcinoma with extensive squamous differentiation presented with a significantly higher rate of nodal metastasis. These findings can be the contributing factors for the unfavorable clinical outcomes seen in patients with urothelial carcinoma and squamous differentiation.