Is Tumor Budding a New Predictor for Early Cystectomy in pT1 High-Grade Bladder Cancer?

Background & Objectives: We aimed to evaluate the risk of progression in high-grade T1 (HGT1) tumors using tumor budding (TB) and other standard clinical and histological features. TB is defined as an isolated cancer cell or a cluster composed of fewer than 5 cells scattered in the stroma and is usually used as a strong predictor of lymph node metastasis in T1 colorectal cancer. Methods: This is an observational longitudinal cohort study involving 168 consecutive patients with HGT1 between 2013 and 2016. Cox regression was performed to analyze the relationship between the clinical and histological features and progression. All slides were blindly assessed by 2 genitourinary pathologists. Budding was determined to be positive when the number of buds was equal to or greater than 6. Results: The median age was 75 years; 152 (90.5%) patients were men, and 49 (29.2%) were positive for TB. At a median follow-up time of 35 months, 33 patients (19.6%) showed progression. Progression was observed in 32.7% of the patients positive for TB and in only 14.3% of those who were negative (p = 0.006). TB was significantly associated with the endoscopic tumor pattern (TP) (papillary/solid) and lymphovascular invasion (LVI). Univariate analysis showed that TB, carcinoma in situ (CIS), TP, LVI, sub-staging, and BCG induction predict progression. The multivariate analysis showed that TB (p = 0.032, hazard ratio 2.1), CIS, TP, and lack of BCG induction were significant for progression. Conclusions: TB is a new and significant pathological variable for predicting progression in HGT1 tumors and can be easily introduced in clinical practice. Its inclusion in the TNM system should be carefully considered, as it may aid early cystectomy decisions.