Clinicopathological Features and Outcomes of Perioperative Treatment for Small Cell Carcinoma of the Bladder

Objective Small cell carcinoma of the bladder (SCCB) is a rare malignant tumor of the bladder. This study aims to explore its clinicopathological features and prognostic factors and to explore the role of perioperative treatment methods.

Methods The clinical data of SCCB patients admitted to West China Hospital, Sichuan University over 8 years from January 2016 to January 2024 were collected. The clinicopathological features of SCCB were summarized. The survival outcomes and prognostic factors were analyzed. The effect of perioperative treatment on the improvement in prognosis was explored.

Results A total of 31 confirmed cases of SCCB were enrolled. We observed a number of clinicopathologic features. All cases had advanced clinical staging, with the T staging status being above T2 in all cases, and distant metastasis was found in 23% of the newly diagnosed cases. A high proportion of the SCCB cases were combined with other histologic types, with 96% showing combination with urothelial carcinoma (UC). The SCCB patients had a poor prognosis, presenting a median survival of 12 months, 1-year overall survival (OS) of 57.9%, and 3-year OS of 27.6%. Patients with extensive-stage SCCB had a significantly worse prognosis than those with limited-stage SCCB did (median OS time of 17.0 months vs. 4.4 months, P<0.05). In limited-stage SCCB, the median OS of patients who underwent radical cystectomy (RC) was 19.9 months, while that of the patients who did not undergo RC was 15.2 months (P<0.05). The OS of patients who received perioperative therapy in combination with RC had longer OS than those who received only RC did (P<0.05). Among these, patients recevied neoadjuvant therapy (NAT) had a significantly longer OS than patients who didn't receive NAT (P<0.05). Subgroup analysis revealed that patients who were responsive to neoadjuvant therapy had longer disease-free survival and longer OS than those who were not responsive did (P<0.05). Lymph node metastasis was an independent factor of poor prognosis (hazard ratio HR=15.21, 95% confidence interval CI: 1.732-133.912, P=0.014). NAT prior to RS was an independent protective factor, significantly reducing the risk of death compared with RC alone (HR=0.03, 95% CI: 0.001-0.724, P=0.031).

Conclusion RC is an effective treatment that prolongs the survival of patients with limited-stage SCCB. RS combined with NAT can further improve their survival.