The clinicopathological characteristics and prognostic value of squamous differentiation in patients with bladder urothelial carcinoma: a meta-analysis

Purpose Urothelial carcinoma with squamous differentiation (UCSD) is the most common histologic variant in bladder cancer (BCa). Previously, some studies have linked the presence of UCSD with the risk of worse survival outcomes in BCa patients. However, such association is still controversial. In this study, we performed a meta-analysis to clarify the clinicopathological characteristics and to further investigate the prognostic value of UCSD in BCa. Methods A systematic literature search was performed in electronic databases including PubMed, Embase, Chinese National Knowledge Infrastructure and Wanfang Data until October 2018. Subgroup analyses were performed according to different treatments and study outcomes. Results Total of 13,284 patients were enrolled in 19 studies which were included in this meta-analysis. The percentage of female patients with UCSD was significantly higher than those with pure urothelial carcinoma. UCSD was correlated with tumor stage T3/T4, tumor grade 3, positive surgical margin, and lymph node involvement. Moreover, the recurrence rate was higher in patients with UCSD after surgery. UCSD was associated with poorer disease-free survival (DFS). No significant difference of cancer-specific survival (CSS) or overall survival (OS) was found on multivariable analysis between the two groups. Conclusions Our study demonstrated that UCSD in BCa was associated not only with unfavorable clinicopathological features, but also with high risk of recurrence and poorer prognosis for DFS. However, UCSD is not independently significant for CSS and OS. Well-designed randomized study with larger sample size is warranted to verify the findings and to further explore the role of UCSD in BCa.