Definitive Chemoradiotherapy Versus Radical Cystectomy for Small Cell Carcinoma of the Bladder: A Multicenter...

To compare oncologic outcomes between radical cystectomy and definitive chemoradiotherapy in patients with nonmetastatic small cell carcinoma of the bladder (SCCB).

We retrospectively reviewed 72 patients with nonmetastatic SCCB treated with curative intent between 2005 and 2021 across 9 tertiary academic institutions. Patients were categorized into a radical cystectomy group (OP, n = 49) or a radiotherapy group (RT, n = 23). Overall survival (OS) and progression-free survival (PFS) were estimated using the Kaplan-Meier method and compared using log-rank tests. To account for baseline imbalances, an IPTW analysis based on propensity scores was performed.

The median follow-up duration was 31.3 months. Median OS was 66.2 months in the OP group and 71.6 months in the RT group (P = .305). The 5-year OS rates were 53.6% and 82.6% in the OP and RT groups, respectively. Stage-stratified and IPTW-adjusted analysis likewise showed no significant differences in OS between groups. On multivariable analysis, nodal involvement was independently associated with worse OS (HR, 9.877; 95% CI, 1.07-91.60; P = .044). Upfront chemotherapy showed a trend toward improved OS, although statistical significance was not reached (HR, 0.14; 95% CI, 0.01-2.25; P = .167). Distant metastasis was the predominant failure pattern in both groups.

Definitive CCRT showed survival outcomes not significantly different from radical cystectomy, though baseline imbalances and small sample size warrant cautious interpretation. Given the predominance of distant failure, systemic chemotherapy remains a key component of treatment, and bladder-preserving CCRT may represent a treatment option for carefully selected patients.