Objective: To study residual tumours at second-look resection in patients resected 4-8 weeks earlier for T1 tumours of the urinary bladder.
Material and methods: All patients randomized in the ongoing Nordic T1G2-G3 Bladder Sparing Study with monitored data available were included in the study. Data on residual tumours at second-look resection were compared to basic patient and tumour characteristics.
Results: There were 72 patients (56%) without and 57 with residual exophytic tumours. In the former group, 20 patients (28%) had carcinoma in situ, compared to 19 (33%) in the latter group. Potentially dangerous tumours (either carcinoma in situ, T1 or Ta grade 3) were observed in 55 patients (43%). Multiple tumours at primary resection were more prone to residual tumour at second-look resection than single tumours. No other tumour or patient characteristics could predict the occurrence of a residual tumour.
Conclusions: Residual tumours are frequently observed at second-look resection 4-8 weeks after primary resection of T1 tumours. The majority of residual tumours detected at this stage are potentially dangerous; therefore, early second-look resection followed by intravesical instillation therapy is mandatory in patients with T1 tumours of the urinary bladder.