INTRODUCTION AND OBJECTIVES: EAU guidelines recommend a single, post-operative instillation (SPI) of intravesical chemotherapy within 24 hours after transurethral resection of a bladder tumor (TURBT) in patients with a low- to intermediate risk non-muscle invasive bladder cancer (NMIBC). However, remarkable variation exists in the use of SPI. Fear for severe and potential deadly complications is likely to contribute to this variation but evidence is limited. Therefore we investigated the risk of severe complications and mortality after SPI in patients with low- and intermediate risk NMIBC. MATERIALS AND METHODS: Patients diagnosed with TaG1G2 urothelial bladder carcinoma between 2009 and 2018 who underwent TURBT were identified in the Netherlands Cancer Registry. Data were supplemented with information on cause of death and severe complications after cancer treatment by re-examining the electronic health records. Severe complications were defined as complications possibly related to SPI which required a prolonged hospital stay of at least 3 days after SPI or readmission within 14 days. Based on these data the 14-day complication risk and the 30-day mortality risk were evaluated. To assess the reasons for not administering SPI, a telephone survey was performed among a subset of Dutch urologists (n=10). RESULTS: In the Netherlands, large variation in the use of SPI is observed. In recent years, the proportion of patients with SPI ranged from 0% to over 80% between hospitals, with a median of 53%. Of the 14,177 patients who received SPI, 18 patients died within 30 days. Three deaths could possibly be attributed to the SPI, resulting in a 30-day mortality risk of 0.02% (3 of 14,177 patients). Of 2,634 patients who had SPI in 2017 and 2018, 47 patients experienced complications which might be linked to SPI, resulting in a 14-day complication risk of 1.78% (47 of 2,634 patients). Complications possibly related to SPI included voiding dysfunction (n=22, 0.84%), pain (n=18, 0.68%) and irritative complaints (n=2, 0.08%). The telephone survey revealed that the most important reasons not to administer SPI include both the fear of severe complications and non-belief in the efficacy of SPI. CONCLUSIONS: In the worst case scenario, the risk of possibly SPI related mortality (0.02%) and severe complications (1.78%) is very low after a TURBT in TaG1G2 bladder tumours followed by SPI of intravesical chemotherapy. Given these data, SPI can be considered a safe treatment in patients with low- or intermediate risk NMIBC who underwent TURBT without (suspected) perforation. As fear of complications and non-belief in the effect of SPI is still present in current practice and considering the substantial variation in use of SPI, our findings suggest that at least a part of patients is wrongly withheld an effective treatment.
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