A Systematic Review and Meta-analysis of Variant Histology in Urothelial Carcinoma of the Bladder Treated with Radical Cystectomy.

The currently available evidence regarding the prognostic and clinical significance of each Variant histology (VH) subtype remains scarce. Therefore, we aimed to assess the prognostic value of VH in patients with Urothelial carcinoma of the bladder (UCB) treated with radical cystectomy.

The PubMed, Web of Science, Cochrane Library, and Scopus databases were searched for articles published before October 2019 according to the Preferred Reporting Items for Systematic Review and Meta-analysis statement. We identified 39 studies comprising 20,544 patients matching our eligibility criteria.

Studies were deemed eligible if they compared overall, cancer-specific, and recurrence-free survival in UCB patients with and without VH. Formal meta-analyses were performed for these outcomes. VH was associated with worse cancer-specific survival (pooled hazard ratio [HR]: 1.37, 95% confidence interval [CI]: 1.24-1.50), overall survival (pooled HR: 1.44, 95% CI: 1.26-1.65), and recurrence-free survival (pooled HR: 1.32, 95% CI: 1.20-1.45). Subgroup analyses revealed that 'micropapillary', 'plasmacytoid', and 'small cell' VH were also associated with worse overall survival (pooled HR: 1.20, 95% CI: 1.02-1.41, pooled HR: 2.03, 95% CI: 1.17-3.52, and pooled HR: 3.32, 95% CI: 1.98-5.59, respectively).

VH in patients with UCB is associated with increased risks of disease recurrence as well as cancer-specific and overall mortality. VH was independently associated with overall survival in the 'micropapillary', 'plasmacytoid', and 'small cell' subgroups. VH should be integrated into prognostic tools to guide risk stratification, treatment planning, and patient counselling. However, caution should be exercised in interpreting the conclusions drawn from this study, given the limitations of the study, which include the heterogeneity of the population of interest and the retrospective nature of the primary data evaluated.

The Journal of urology. 2020 Jul 27 [Epub ahead of print]

Keiichiro Mori, Mohammad Abufaraj, Hadi Mostafaei, Fahad Quhal, Pierre I Karakiewicz, Alberto Briganti, Shoji Kimura, Shin Egawa, Shahrokh F Shariat

Department of Urology, Medical University of Vienna, Vienna, Austria., Cancer Prognostics and Health Outcomes Unit, University of Montreal Health Centre, Montreal, Canada., Department of Urology, Vita Salute San Raffaele University, Milan, Italy., Department of Urology, The Jikei University School of Medicine, Tokyo, Japan.