Neoadjuvant chemotherapy in bladder cancer: Clinical benefit observed in prospective trials computed with restricted mean survival times

Purpose: Neoadjuvant chemotherapy (NAC) is the standard of care for eligible patients with cT2-4a N0 M0 bladder cancer undergoing surgical resection. The extent to which (and if) NAC increases patient survival is not clear as clinical trials and meta-analyses have generated both negative and "borderline" positive results. The novel method of calculating restricted mean survival times (RMST) may provide a more meaningful way to quantify treatment efficacy due to inherent statistical limitations of conventional hazard ratios. In this study we analyzed the survival benefit attributable to NAC in bladder cancer by calculating RMST of previously published clinical trials.

Materials and methods: All published randomized controlled clinical trials of bladder cancer with available survival data comparing NAC plus radical cystectomy with cystectomy alone were included. RMSTs were calculated for each cohort at the 5-year and total follow-up time periods, comparing the NAC and radical cystectomy groups. Fixed effect meta-analysis of the 5-year RMSTs was then performed to calculate the net impact of NAC on overall survival.

Results: For 2 among 7 included trails, RMST analysis changed the statistical significance. The SWOG 8,710 trial that had previously suggested a survival benefit associated with NAC (P = 0.06) was found to have a clearer beneficial association by 5-year RMST (6.5 month benefit; P = 0.01) and total follow-up RMST (13.6 month benefit over 168 months; P = 0.04). The International Collaboration of Trialists trial that had previously suggested a survival benefit with NAC (P = 0.04) was found to have a beneficial association by total follow-up RMST (6.7 months benefit over 120 months; P = 0.04) but not 5-year RMST (P = 0.10). The interpretation of other trials did not change. Fixed effect meta-analysis suggested a clinically significant overall survival benefit associated with NAC (3.2 months benefit over 60 months; P < 0.01).

Conclusions: Evaluation of published randomized controlled trials using RMSTs strengthens the association of neoadjuvant chemotherapy with survival benefit in bladder cancer. As RMST may enable improved detection of clinical benefit when compared to conventional statistical methods, consideration should be given to RMST-based endpoints in future clinical trial design.