Treatment and survival of non-metastatic small cell carcinoma of the bladder from multiple centers in China

Small cell carcinoma of the bladder (SCCB) is a rare, highly malignant neuroendocrine tumor. This study attempted to analyze tumor characteristics, treatments and clinical outcomes in China. We conducted a retrospective analysis of patients diagnosed with non-metastatic SCCB at multi-institutions between January 2007 and January 2022. The Kaplan-Meier method was used to calculate survival. A total of 20 patients were included. 10 had localized disease (T1-2N0), and 10 had locally advanced disease (≥ T3 or N+). 13 received local treatment (partial cystectomy or transurethral resection of the bladder tumor) and 7 received radical treatment (radical cystectomy or radiotherapy). A total of 18 patients (90%) received chemotherapy (CT), either neoadjuvant CT (n = 5) or adjuvant CT (n = 13). The median OS for the receiving local treatment was 65.3 months (95% CI 0 to 138 months) and the corresponding 1-year, 2-year, and 3-year OS was 77%, 54%, and 54%, respectively. The median OS for the receiving radical treatment was not reached and the corresponding 1-year, 2-year, and 3-year OS was 100%, 100%, and 75%, respectively. The median PFS for receiving local treatment was 13.8 months (95% CI 9.3 to 18.3 months) and the corresponding 1-year, 2-year, and 3-year PFS was 46%, 31%, and 31%, respectively. The median PFS for the receiving radical treatment was not reached and the corresponding 1-year, 2-year, and 3-year PFS was 83%, 56%, and 56%, respectively. This study reported the largest cohort of non-metastatic SCCB among Chinese population. Given its metastatic potential, CT remained an essential part of the treatment. The survival outcomes of radical cystectomy and RT in non-metastatic SCCB were encouraging.