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

Abstract

Study Type - Prognosis (cohort). Level of Evidence 2a. What's known on the subject? and What does the study add? The subject of mortality and survival rates after radical cystectomies in high-volume hospitals in comparison to low-volume hospitals has been extensively studied. Postoperative mortality is known to be significantly lower with high-volume providers, but for survival rates there was only a trend forwards this finding. For this reason, we performed this Dutch population-based study on survival rates, to see if we had enough power to support this trend with significant findings. To our knowledge, this is the first study of good quality showing a significant beneficial effect for survival in high-volume hospitals.

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.