Survival after treatment for carcinoma invading bladder muscle: a Dutch population-based study on the impact of hospital volume

OBJECTIVE To examine the volume-outcome relationship for carcinoma invading bladder muscle (MIBC) with respect to differences in survival rates among all hospitals in the Netherlands as a guide for regionalization initiatives. MATERIALS AND METHODS This population-based retrospective study included all patients (n = 13 033) newly diagnosed with MIBC during the period 1999-2008 in the Netherlands, selected from the Netherlands Cancer Registry. Data were collected on demographics, morphology, stage at diagnosis and after surgery, primary treatment, vital status and date of follow-up or death. The relative survival rate (RSR) per treatment was analysed for age, stage and hospital surgical volume. RESULTS Overall 5 and 10-year RSR for all treatments of MIBC was 32% and 25%, respectively. Although 71.7% of the patients featured stages II and III, radical cystectomy was only performed in only 42% and 44% of these patients, respectively. Relative survival for MIBC remained unchanged in the two consecutive time periods (1999-2003 and 2004-2008). In all, 34% of patients diagnosed in low-volume hospitals (<10 cystectomies/year) underwent cystectomy vs 42% of those diagnosed in high-volume hospitals (P = 0.000). In a multivariate analysis long-term survival (>30 days after surgery) was significantly lower in patients after cystectomy for stage II/III in low-volume hospitals (hazard ratio [HR] 1.17, P = 0.036). A high lymph node count (>20) was associated with a lower risk of death (HR 0.52, P = 0.000). CONCLUSIONS The 10-year RSR for patients with MIBC in the Netherlands was modest (25%) and has remained unchanged in the last decade. The chance of undergoing cystectomy is significantly higher in high-volume hospitals. Long-term survival after cystectomy is higher in high-volume hospitals. Regionalization of bladder cancer treatments could improve overall outcomes.