A New and Highly Prognostic System to Discern T1 Bladder Cancer Substage

BackgroundManagement of T1 bladder cancer (BCa) is controversial.ObjectiveEvaluate the impact of substage on the clinical outcome of T1 BCa.Design, setting, and participantsThe T1 diagnosis of 134 first-diagnosis BCa patients from two university hospitals was confirmed. For the T1 substage, we used a new system that discerns T1-microinvasive (T1m) and T1-extensive-invasive (T1e) tumors. We then determined the invasion of the muscularis mucosae–vascular plexus (MM-VP): T1a (invasion above the MM-VP), T1b (invasion in the MM-VP), or T1c (invasion beyond the MM-VP). If the MM-VP was not present at the invasion front, the case was assigned to T1a or T1c. All patients were initially managed conservatively (with bacillus Calmette-Guérin).MeasurementsMultivariable analyses for progression and disease-specific survival (DSS).Results and limitationsMedian follow-up was 6.4 yr (interquartile range: 3.3–9.2 yr). Progression to ≥T2 was observed in 40 patients (30%), and 19 patients (14%) died of BCa. The MM-VP was not present at the invasion front in 50 patients (37%). T1 substage was as follows: 40 T1m and 94 T1e; 81 T1a, 18 T1b, and 35 T1c. In multivariable analyses, substage (T1m/T1e) was significant for progression (p = 0.001) and DSS (p = 0.032), whereas substage according to T1a/T1b/T1c was not significant. Female gender (p = 0.006) and carcinoma in situ (p = 0.034) were also significant predictors of progression. The main limitation to the study is absence of a repeat transurethral resection.ConclusionsSubstage according to the new system (T1m and T1e) was user-friendly, possible in 100% of cases, and very predictive of T1 BCa behavior. Future studies may ultimately lead to the incorporation of this new substaging system in the TNM classification system for urinary BCa.