Treatments and survival outcomes of patients with synchronous and metachronous metastatic bladder cancer: A population-based nationwide cohort study

Abstract

OBJECTIVE: To describe and compare clinicopathological characteristics, treatment patterns and overall survival outcomes of contemporary patients diagnosed with synchronous (smBC) or metachronous metastatic bladder cancer (mmBC) in the Netherlands. METHODS: All patients newly diagnosed with bladder cancer in the Netherlands in 2020-2023 were identified through the Netherlands Cancer Registry. The smBC group consisted of patients with mBC at initial diagnosis in 2020 - 2023. The mmBC group included all patients who developed metastatic disease <3 years after being diagnosed with muscle-invasive bladder cancer (MIBC) between January 2020 - June 2022 and was stratified into early (≤6 months) and late mmBC (>6 months). Vital status was available until January 2025. RESULTS: The cohort included 2375 patients (1584 smBC, 371 early mmBC and 420 late mmBC). Lung and liver metastases were equally common across subcohorts; visceral disease was more common among mmBC patients. Less than half of patients received systemic therapy in all subcohorts (carboplatin most common for smBC and late mmBC patients; immunotherapy for early mmBC patients). Median OS regardless of treatment was 4.6, 3.9 and 7.4 months for smBC, early mmBC and late mmBC patients, respectively. Among those who received systemic treatment, median OS was 11.8, 8.5 and 12.6 months. Median OS differences were smaller when further restricting to systemic treatment-naïve patients. CONCLUSIONS: Patient populations with smBC and early and late mmBC showed moderate differences in patient or disease characteristics that may be of clinical relevance. Many patients were unable to receive systemic treatment, with only small differences between groups, resulting from prior treatment, emphasizing the unmet need among both smBC and mmBC patients. Patients with mBC have a poor prognosis, irrespective of time to metastasis with limited OS differences.