Evaluation of histological variants of upper tract urothelial carcinoma as prognostic factor after radical nephroureterectomy.

PURPOSE:To evaluate the impact of variant histology on patients with upper tract urothelial carcinoma (UTUC) survival outcomes. MATERIALS AND METHODS:A total of 519 patients underwent radical nephroureterectomy without neoadjuvant therapy for UTUC at a single institution between May 2003 and December 2019. Multivariate Cox regression analysis evaluated the impact of variant histology on progression-free survival (PFS), cancer-specific survival (CSS), and overall survival (OS). RESULTS:Among 84 patients (16.2%) with variant histology, the most frequent variant type was squamous cell differentiation (64.3%), followed by glandular differentiation (25.0%) and sarcomatoid variant (2.4%). They showed pathologically advanced T stage (for ≥ T3, 59.5% vs 33.3%, p < 0.001), higher tumor grade (96.4% vs 85.7%, p = 0.025), and higher rates of lymph node metastasis (17.9% vs 7.8%, p = 0.015), angiolymphatic invasion (41.7% vs 25.7%, p = 0.003), tumor necrosis (57.1% vs 29.0%, p < 0.001) and positive surgical margin (13.1% vs 5.7%, p = 0.015). On multivariate Cox regression analyses, variant histology was significantly associated with worse PFS (hazard ratio [HR] 2.23; 95% confidence interval [CI] 1.55-3.21; p < 0.001), CSS (HR 2.67; 95% CI 1.35-5.30; p = 0.005) and OS (HR 2.22; 95% CI 1.27-3.88; p = 0.005). In subgroup analysis, no significant survival gains of adjuvant chemotherapy occurred in patients with variant histology. CONCLUSIONS:Variant histology was associated with adverse pathologic features and poor survival outcomes. Our results suggest that patients with variant histology may require a close follow-up schedule and novel adjuvant therapy other than chemotherapy postoperatively.