Prognostic significance of tumor budding in gastrointestinal tumors

Tumor budding describes the presence of single tumor cells or small tumor cell clusters at the invasion front of carcinomas. It is currently thought to be the result of epithelial-mesenchymal transformation. Tumor budding can be appreciated histologically during routine evaluation of malignant polyps or surgical specimens of malignant tumors. Many studies have been published assessing cancers in all locations from the esophagus to the rectum, almost always reporting similar results. This seems especially remarkable as a generally accepted definition of how budding must be evaluated is still lacking. Regardless of the location, tumor budding generally is associated with nodal metastases and aggressive behavior, and it is mostly independent from other adverse factors. While the prognostic value of tumor budding is evident, especially in stage II colorectal cancers, it still has no therapeutic implications. This is owing to the heterogeneity of the performed studies and the lack of oncological studies, which are urgently needed.