Variant urothelial carcinoma (VUC, defined herein as urothelial carcinoma with any histological variant) is frequently observed at an advanced stage. However, the efficacy of systemic chemotherapy against VUC in metastatic disease has rarely been reported. This study assessed the therapeutic response and survival outcomes of platinum-based chemotherapy as first-line treatment in patients with metastatic VUC.

We retrospectively analyzed consecutive patients with metastatic bladder and upper urinary tract cancer who received gemcitabine plus cisplatin (or carboplatin) at the University of Occupational and Environmental Health Hospital between November 2008 and November 2022. Progression-free survival and overall survival were evaluated using the Kaplan-Meier method and Cox proportional hazard models.

Out of 131 patients recorded, 86 (65.6%) had pure urothelial carcinoma (PUC) and 45 (34.4%) had VUC. The most common variant element was squamous differentiation (44.4%). Compared to those with PUC, patients with VUC showed a comparable objective response rate (33.3% vs. 41.9%, p=0.451) and disease control rate (64.5% vs. 75.6%, p=0.221). They also had poorer progression-free survival (median=4.9 months vs. 7.9 months, p=0.014) and overall survival (median=10.9 months vs. 18.2 months, p=0.037) than those with PUC. On multivariate analysis, VUC was an independent predictor of progression (hazard ratio=1.79; 95% confidence interval=1.19-2.69; p=0.005) and mortality (hazard ratio=1.64; 95% confidence interval=1.08-2.48; p=0.020).

Although the response of metastatic VUC to platinum-based chemotherapy was not inferior to that of PUC, VUC had progressed faster than PUC. VUC was significantly associated with a poor prognosis after platinum-based chemotherapy as first-line treatment.