Prognostic role of substaging in T1G3 transitional cell carcinoma of the urinary bladder

This study was conducted to test a new substaging system in a population of patients with stage T1 bladder cancer (BC) at diagnosis and assess its prognostic role in terms of disease progression and disease-specific survival (DSS). Patients with primary stage T1G3 urothelial carcinoma of the bladder were stratified according to the following models: i) T1a [the tumour does not infiltrate the muscularis mucosae-vascular plexus, (MM-VP)]; T1b (the tumour partially infiltrates the MM-VP); and T1c (the tumour infiltrates and invades the MM-VP). ii) T1m (diameter of tumour infiltrating the lamina propria ≤0.5 mm under a high-resolution microscope; and T1e (diameter of tumour infiltrating the lamina propria >0.5 mm). Age, gender, tumour size and multifocality were not found to be of statistical significance. Using the T1a/T1b/T1c system, patients with stage T1a disease exhibited a 5- and 10-year progression rate of 13.3 and 20%, respectively, without reaching statistical significance. Moreover, patients with stage T1a disease exhibited a 5- and 10-year DSS of 93.3 and 73.3%, respectively, which was higher compared to T1b and T1c but not statistically significant. Using the T1m/T1e system, patients with stage T1m disease exhibited a disease progression rate of 8.3 and 16.7% at 5 and 10 years, respectively, which was not statistically significant. Moreover, patients in group T1m presented with DSS rates of 91.7 and 83.3% at 5 and 10 years, respectively, which were higher compared to those in the T1e group (71.4 and 60.7%), although not reaching statistical significance. In conclusion, in our study, neither of the two substaging systems of stage T1 BC reached the prognostic conventional significance level for tumour progression or DSS.