Systematic assessment of protein phenotypes characterizing high-grade tumour budding in mismatch repair-proficient colorectal cancer

Aims: A tumour bud is defined as a single tumour cell or tumour cell cluster of up to five cells at the invasive tumour front. Significant differences in survival have been detected in colorectal cancer patients with low- compared to high-grade budding. The aim of this study was to identify potential multi-marker phenotypes characterizing low- and high-grade budding in mismatch repair (MMR)-proficient colorectal cancer. Methods and results: Established and promising prognostic proteins such as epidermal growth factor receptor (EGFR), pERK, RHAMM, RKIP, beta-catenin, E-cadherin, pAKT, p16, p21, Ki67, Bcl-2, vascular endothelial growth factor (VEGF), apoptotic protease activating factor-1 (APAF-1), MUC1, EphB2, matrix metalloproteinase 7, pSMAD2, CDX2, laminin5 gamma 2 and MST1 were analysed on 208 MMR-proficient colorectal cancers with complete clinicopathological data. The most accurate markers for predicting high-grade budding (more than six tumour buds) were EphB2 (P < 0.001), Bcl-2 (P < 0.001), RKIP (P < 0.001), E-cadherin (P = 0.004), laminin5 gamma 2 (P = 0.004) and APAF-1 (P = 0.005). On multivariable analysis, only loss of Bcl-2 (P < 0.001) and EphB2 (P < 0.001) were independent predictors of high-grade budding. Bcl-2-/EphB2- tumours were more frequently poorly differentiated (P < 0.001), of advanced pT stage (P = 0.002), lymph node positive (P = 0.023), presented vascular (P = 0.053) and lymphatic invasion (P = 0.005) and had a negative impact on patient survival (P = 0.012). Conclusions: The multi-marker phenotype EphB2-/Bcl-2- is an independent predictor of high-grade budding and implies increased aggressive behaviour in MMR-proficient colorectal cancer.