146P - Comparison of the survival outcomes between primary and secondary muscle-invasive bladder cancer: A propensity score-matched Chinese cohort

Background

Studies have classified muscle-invasive bladder cancer (MIBC) into primary (initially muscle-invasive, PMIBC) and secondary subtypes (initially non-muscle-invasive but progressed, SMIBC), in which controversial survival outcomes were demonstrated. However, a relevant Chinese cohort is yet to be reported.

Methods

Patients diagnosed with PMIBC or SMIBC at West China Hospital from January 2009 to June 2019 were retrospectively included. The Kruskal–Wallis and Fisher tests were employed to compare the baseline clinicopathological characteristics. Furthermore, Kaplan–Meier curves and Cox competing proportional risk model were used to compare the PMIBC and SMIBC survival outcomes. Then, propensity score matching (PSM) was employed to reduce the bias caused by confounders and subgroup analysis was used to confirm the outcomes.

Results

A total of 405 MIBC patients were enrolled, including 286 PMIBC and 119 SMIBC patients, with a mean age of 64.66 years and 67.29 years and a mean follow-up of 27.54 months and 53.3 months, respectively. The SMIBC group had a higher proportion of older patients (17.65% vs. 9.09%), chronic disease (32.77% vs. 22.38%), and neoadjuvant chemotherapy (19.33% vs. 8.04%). Before matching, SMIBC had a lower risk of overall mortality (OM) (hazard ratios [HR] 0.60, 95% confidence interval [CI] 0.41–0.85, P = 0.005) and cancer-specific mortality (CSM) (HR 0.64, 95% CI 0.44–0.94, P = 0.022) after the initial diagnosis. However, higher risks of OM (HR 1.47, 95% CI 1.02–2.10, P = 0.038) and CSM (HR 1.58, 95% CI 1.09–2.29, P = 0.016) were observed for SMIBC once it became muscle-invasive. After PSM, the baseline characteristics of 146 patients (73 for each group) were well matched, and SMIBC was confirmed to have an increased CSM risk (HR 1.83, 95% CI 1.09–3.06, P = 0.021) than PMIBC after muscle invasion.

Conclusions

This study demonstrated that SMIBC, compared with PMIBC, had worse survival outcomes once it became muscle-invasive and suggested that specific attention should be paid to non-muscle-invasive bladder cancer with a high progression risk.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

The author.

Funding

Has not received any funding.

Disclosure

The author has declared no conflicts of interest.