1. Department of Urology, Institute of Urology, West China Hospital, Sichuan University, Chengdu, Sichuan. P.R. China.
2. Center of Biomedical big data, West China Hospital, Sichuan University, Chengdu, Sichuan, P.R. China.
Objective: Studies have showed that different follow-up starting points might potentially impact the comparison between primary (PMIBC) and secondary muscle-invasive bladder cancer (SMIBC), but the only previous meta-analysis did not differentiate the follow-up starting points of included studies. With more trials published, we aim to update the meta-analysis comparing PMIBC and SMIBC.
Methods: PubMed, Embase, Cochrane Library and ClinicalTrial.gov. systematically searched. Literatures comparing the survival outcomes of PMIBC and SMIBC were selected. Outcomes of cancer-specific mortality (CSM), overall mortality (OM) and recurrence-free survival (RFS) were pooled and grouped based on the starting point of follow-up (after initial diagnosis or radical cystectomy (RC)). Newcastle-Ottawa Scale (NOS) and funnel plot were employed to assess the study quality and publication bias, respectively.
Results: A total of 17 high-quality studies were selected, with 5558 patients aged from 59.8 to 72.7 (mean value) involved. The male-to-female ratio was roughly 4:1 (4390/1124). SMIBC had lower risk of CSM after initial diagnosis (HR 0.81, 95%CI 0.67-0.98, P=0.03, I2=70%), but higher risk of CSM after RC (HR 1.45, 95%CI 1.27-1.65, P<0.00001, I2=64%). In terms of OM and recurrence, outcomes were pooled only after RC, which both turned out to be higher for SMIBC (OM: HR 1.50, 95%CI 1.30-1.73, P<0.00001, I2=0%; Recurrence: HR 1.66, 95%CI 1.36-2.02, P<0.00001, I2=48%). No obvious publication bias was observed from funnel plot.
Conclusion: The current study suggested SMIBC had higher risk of CSM, OM and recurrence after RC, but lower risk of CSM after initial diagnosis.
Keywords: primary muscle-invasive bladder cancer, secondary muscle-invasive bladder cancer, initial diagnosis, radical cystectomy, cancer-specific mortality, overall mortality, recurrence