Tumour budding in colorectal cancer (CRC) is a recognized prognostic parameter. Aim of this study is to address the use of cytokeratin immunostaining for visualization and scoring of tumour buds.
METHODS
Ten hotspots (0.238 mm(2) ) of peritumoural (PTB) and intratumoural (ITB) budding were evaluated in surgical resections from 215 patients. The budding counts in the 10 densest regions anywhere in the tumour were combined into an overall tumour budding (OTB) score. The PTB, ITB and OTB hotspot with the maximum budding count was then evaluated. Finally, continuous and cut-off values of 10 buds/HPF (PTB10HPF ), 5 buds/HPF (ITB10HPF ) and 8 buds/HPF (OTB10HPF ) were used to categorize budding counts into low/high-grade scores.
RESULTS
All budding scores were highly correlated. PTB and ITB counts were associated with many clinicopathological features including tumour stage, lymph node and distant metastasis, venous and lymphovascular invasion and disease-free survival (DFS) (all p<0.05). Analyses of OTB counts recapitulated these associations, including a lower DFS with a greater number of tumour buds (p=0.0309; HR (95%CI): 1.032 (1.003-1.062)). One OTB hotspot performed similarly as ten OTB hotspots in terms of relationship with outcome. These statistical significances were largely lost when cut-offs were applied to PTB, ITB or OTB counts.
CONCLUSIONS
OTB count in a single hotspot on cytokeratin-stained CRC tissue sections is a fast and reliable prognostic scoring system for the assessment of tumour budding. This approach should be considered in future studies. This article is protected by copyright. All rights reserved.
