The prognostic value of T1 bladder cancer substaging: a single institution retrospective study.

OBJECTIVE To evaluate the prognostic value of the depth of lamina propria invasion in patients with T1 bladder cancer. SUBJECTS AND METHODS 200 patients were treated between the years 2002 and 2009. Tumours with depth of invasion above the muscularis mucosae level were categorised as pT1a and those with depth of invasion up to or beyond the muscularis mucosae as pT1b. RESULTS Categorisation for pT1a and pT1b was performed in 176 of 200 patients (88%). In 10 patients a muscle-invasive tumour was found in re-transurethral resection samples. 131 (79%) of 166 analysed patients had pT1a tumour and 35 (21%) had pT1b tumour. During the follow-up, in 101 (61%) patients the tumour had recurred and in 27 (16.3%) the tumour had progressed. Of all the investigated parameters, T1 substaging (p < 0.0001), grade (p = 0.0003) and the number of bacillus Calmette-Guérin instillations (p = 0.0490) were significant in predicting progression. The only significant factor for disease-specific survival was T1 substaging in univariable (p = 0.0008) and multivariable (hazard ratio 4.407) analysis. T1 substaging (p = 0.0149) and tumour multiplicity (p = 0.0448) have a statistically significant prognostic value with respect to overall survival. CONCLUSIONS Deep invasion of the lamina propria is a significant adverse prognostic factor for tumour progression, disease-specific survival and overall survival.