Tumour 'budding' and its relationship to p53 and Bcl-2 expression in colorectal cancer

The formation of poorly-differentiated clusters of cancer cells in the tumour growth zone, defined as "tumour budding", is a likely factor determining the biological malignancy of colorectal cancer (CRC). The aim of the study was to evaluate tumour budding in the CRC growth zone and to analyse its relationship to chosen anatomoclinical parameters, and to p53 and Bcl-2 protein expression in the tumour budding and in the main tumour mass. Fifty-seven colorectal cancers, classified as pT3 and G2, were used for analysis. Immunohistochemical investigations were performed using the anti-human p53 and Bcl-2 protein monoclonal antibodies (Dako/p53, No M7001 and Dako/Bcl-2, No M 0887, respectively). It has been found that p53 overexpression in the primary tumour and the presence of lymph node metastases correlate with strongly-positive tumour budding (p < 0.04 and p < 0.000001). However, low expression of p53 protein in the primary tumour and lack of lymph node metastases was statistically significantly correlated with the absence of tumour budding. A statistically significant correlation was shown between p53 protein expression in the tumour budding and expression of p53 in the primary tumour and lymph node metastases (p < 0.05). We also observed a statistically significant correlation between Bcl-2 protein expression in the tumour budding and its expression in the primary tumour and lymph node metastases (p < 0.05). These data suggest that tumour budding of cancer, in combination with other markers, may provide more information about the biological behaviour of colorectal cancer.