Oncological Outcome of Primary and Secondary Muscle-Invasive Bladder Cancer: A Systematic Review and Meta-analysis.

Conflicting results of survival outcomes for primary and secondary muscle-invasive bladder cancer (MIBC) have been reported in previous studies. Primary MIBC is defined as presentation of muscle-invasive disease at initial diagnosis while secondary MIBC presumes that non-muscle invasive disease later progressed to MIBC. Due to the varying reports, we conducted a systematic review and meta-analysis to compare survival outcomes between the two groups. Relevant studies were retrieved from Medline, Embase, the Cochrane Library, and Scopus using a comprehensive search approach. Cancer-specific survival (CSS) was the outcome measure. A total of 14 studies involving 4,075 cases were included. Patients with secondary MIBC were significantly correlated with worse CSS in model I (pooled HR: 1.29, 95% CI: 1.07-1.56, P = 0.008). The results of sensitivity analyses indicated that the omission of any single study each time did not have a significant impact on the combined risk estimates. Egger's test suggested no publication bias among these studies. The European Organization for Research and Treatment of Cancer (EORTC) risk score offers the possibility of stratifying the secondary MIBC patients into different risk groups. In high-risk NMIBC, timely radical cystectomy should be considered. Further study is required to assess the multimodal therapy in both high-risk NMIBC and secondary MIBC patients as well as to evaluate genetic and molecular drivers of tumor induction, promotion, and progression.