Trends in neoadjuvant chemotherapy use and oncological outcomes for muscle-invasive bladder cancer in Japan: a multicenter study

Objective Despite benefits of neoadjuvant chemotherapy (NAC), the adoption of guideline recommendations for NAC use in patients with muscle-invasive bladder cancer (MIBC) has been slow. We aimed to evaluate temporal trends in NAC use and oncological outcomes in a representative cohort of patients with MIBC. Methods We included 532 patients from 4 hospitals who underwent radical cystectomy (RC) for ≥ cT2 MIBC in 1996-2017. We retrospectively evaluated temporal changes in NAC use and progression-free and overall survival. Candidates for NAC were administered with either cisplatin- or carboplatin-based regimens. The impact of NAC on oncological outcomes was examined using multivariate Cox regression analysis with inverse probability of treatment weighting (IPTW) models. Results Of 532 patients, 336 underwent NAC followed by RC (NAC group) and 196 underwent RC alone (Ctrl group). NAC use significantly increased from 10% (1996-2004) to 83% (2005-2016). The number of patients administered with cisplatin- and carboplatin-based regimens was 43 and 280, respectively. Oncological outcomes in the NAC group were significantly improved compared to those in the Ctrl group. Multivariable analysis with IPTW models revealed that NAC significantly improved oncological outcomes in patients with MIBC. A nomogram for 5-year overall survival predicted 16% improvement in patients undergoing NAC. Conclusions NAC use for MIBC increased after 2005. Platinum-based NAC for MIBC potentially improves oncological outcomes.