Comparison of expected treatment outcomes, obtained using risk models and international guidelines, with observed treatment outcomes in a Dutch cohort of patients with non-muscle-invasive bladder cancer treated with intravesical chemotherapy.

Objective: To compare the risks according to the American Urological Association (AUA), EAU, European Organization for Research and Treatment of Cancer (EORTC) and Club Urológico Español de Tratamiento Oncologico (CUETO) classifications with real outcomes in a cohort of patients in the Netherlands, and to confirm that patients who were undertreated according to these risk models have worse outcomes than adequately treated patients.

Patients And Methods: Patients treated with complete transurethral resection of bladder tumour and intravesical chemotherapy were included. Not all patients would have received intravesical chemotherapy had they been treated to current standards, and thus comparison of the observed outcomes in our Dutch cohort vs expected outcomes based on the EORTC risk tables and CUETO scoring model was possible. The cohort was reclassified according to the definitions of five index patients (IPs), as defined by the AUA guidelines, and three risk groups, defined according to the EAU guidelines, to compare the outcomes of undertreated patients with those of adequately treated patients.

Results: A total of 1001 patients were available for comparison with the AUA definitions and 728 patients were available for comparison with the EORTC and CUETO models. There was a large overlap between the observed outcomes and expected recurrence and progression probabilities when comparison was made using the EORTC risk tables. The observed recurrence outcomes were in general higher than the expected probabilities according to the CUETO risk classification, especially in the long term. No differences in progression were found when comparing these two models to the Dutch cohort. Patients who were undertreated according to the guidelines showed, in general, a higher risk of developing recurrence and progression. Limitations are i.a. its retrospective nature and the differences in grading system.

Conclusion: Comparisons between the observed outcomes in our Dutch cohort and the expected outcomes based on EAU and CUETO risk models and the EORTC and AUA guidelines showed that lack of adherence to existing guidelines translates into worse outcomes.