Prognostic Value of Variant Histology in Upper Tract Urothelial Carcinoma Treated with Nephroureterectomy: A Systematic Review and Meta-Analysis.

Purpose: We sought to assess the prognostic value of variant histology in patients with upper tract urothelial carcinoma treated with radical nephroureterectomy.
Materials and Methods: We searched PubMed®, Web of Science™, Cochrane Library and Scopus® databases in May 2019 according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) statement. Studies were deemed eligible if they compared overall, cancer specific and recurrence-free survival in patients with upper tract urothelial carcinoma with or without variant histology. Formal meta-analyses were performed for these outcomes.
Results: We identified 32 studies with 16,052 patients, including 26 studies with 12,865 patients that were eligible for the meta-analysis. Variant histology was associated with poor outcomes in terms of cancer specific (pooled HR 2.00, 95% CI 1.57 to 2.56), overall (pooled HR 1.76, 95% CI 1.51 to 2.04) and recurrence-free survival (pooled HR 1.64, 95% CI 1.42 to 1.89). Subgroup analyses revealed that micropapillary (pooled HR 3.02, 95% CI 1.71 to 5.34), and squamous and/or glandular variant histologies (pooled HR 1.48, 95% CI 1.14 to 1.92) were also associated with poor cancer specific survival.
Conclusions: Variant histology in patients with upper tract urothelial carcinoma is associated with an increased risk of cancer specific and overall mortality and disease recurrence. Furthermore, variant histology was independently associated with cancer specific survival in the micropapillary, and squamous and/or glandular variant histology subgroups. It may be useful to incorporate variant histology into prognostic tools that help guide patients and physicians in selecting appropriate treatment strategies for upper tract urothelial carcinoma.