Should a fourth category be added to the international tumor budding consensus conference tumor budding scoring system in colorectal adenocarcinomas?

The aim of this study was to investigate the relationship between tumor budding (TB) and clinicopathologic prognostic criteria in colorectal adenocarcinomas and to discuss the inclusion of the fourth group in the scoring system. A total of 131 cases were included in the study. TB was scored according to the classical 3-tiered scoring system and our proposed 4-tiered scoring system: BD0 (no buds), BD1* (1-4 buds), BD2 (5-9 buds), and BD3 (≥10 buds). Cytokeratin staining was applied to 80 randomly selected cases and TB scoring was re-evaluated. TB was not observed in 31 (23.7%) of 131 cases and was categorized as BD0. Patients with BD0 budding had lower pT category, AJCC stage, tumor grade, less lymph node metastasis, lymphovascular invasion, tumor deposits (p < 0.05), and longer overall survival than BD1* patients (log-Rank p: 0.018). There was significant compatibility between the evaluation of TB with H&E and cytokeratin (kappa: 0.727, p < 0.001). In conclusion, we think it is valuable to add the "BD0" category to the International Tumor Budding Consensus Conference (ITBCC) scores. However, more research with larger cohorts is needed for clinical applicability. H&E staining is sufficient for the assessment of budding, except in conditions such as increased inflammation where the tumor-stroma interface may be obscured.