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T1 high-grade (T1HG) urothelial carcinoma of the bladder presents a persistent clinical challenge: despite uniform high-risk classification under EAU guidelines, BCG failure and disease progression rates range from 10% to 40% across published series. Standard clinicopathological variables do not adequately explain this heterogeneity. Three pathological parameters evaluable from routine TURBT specimens—T1 substaging by lamina propria invasion depth, tumour budding at the invasion front, and E-cadherin (CDH1) immunohistochemistry—share a common mechanistic basis in CDH1-driven partial epithelial-to-mesenchymal transition and may refine escalation-oriented risk stratification without requiring additional tissue or molecular testing. We conducted a narrative critical review of PubMed/MEDLINE (January 2000–February 2026; 28 included studies) to evaluate the quantitative evidence for each parameter, with emphasis on reproducibility and BCG-specific outcome data. T1 substaging carries the strongest evidence: pooled progression HR 3.29 (95% CI 2.39–4.51) across 36 studies (n = 6781), with BCG failure of 41% vs. 21% in a centralised BCG-treated registry cohort of 264 patients on multivariable analysis. Tumour budding shows consistent adverse associations in BCG-treated pT1 NMIBC; zero progression was observed in the low-budding subgroup in the only available BCG-specific full-text cohort. CDH1 IHC is directionally supportive but limited by scoring heterogeneity (I2 = 63%). All three parameters are mechanistically coherent and assessable from routine TURBT slides. Prospective validation with pre-specified thresholds and standardised scoring protocols is required before clinical implementation can be recommended.
Sala-González et al. (Wed,) studied this question.