IntroductionThe aim of our study was to evaluate the prognostic impact of tumor infiltration depth of the lamina propria and invasion or non-invasion of the muscularis mucosa of pT1 bladder tumors, studying recurrence and progression rate, overall survival, disease-free survival and progression-free survival. Patients and methodsAll slides were reviewed to determine the presence or absence of muscularis mucosa, invasion above (pT1a) or below (pT1b) the muscularis mucosa, and the invasion depth of the lamina propria (pT1m: a single focus of lamina propria invasion ≤0.5mm, pT1e: single focus >0.5mm of lamina propria invasion or multiple micro-invasive area). ResultsDepending on the invasion of the muscularis mucosa, the rate of recurrence and progression was more frequent in pT1b tumors in comparison to patients classified pT1a, with a recurrence rate of 84.6% (p=0.0012) and a progression rate of 38.5% (p=0.003). Depending on the degree of invasion of the lamina propria, the rate of recurrence and progression was more frequent for pT1e tumors in comparison to pT1m, with a recurrence rate of 57.2% (p=0.05) and a progression rate of 17.9% (p=0.11). Disease-free survival was 70.3 months for pT1a tumors against 53.6 months for pT1b tumors (p=0.046), and it was 61.7 months for pT1e tumors against 55.5 months for pT1m tumors (p=0.85). ConclusionThe classification of bladder tumors based on the invasion of the lamina propria has proved its efficiency through the recurrence rate and the progression rate among our patients.