The prognostic value of tumor budding in invasive breast cancer

Abstract

We investigated the prognostic value of tumor budding in 160 cases of operable invasive ductal carcinoma, not otherwise specified (IDC-NOS). The number of buds was counted in H&E slides with a maximal invasive margin in a 0.950mm(2) field of vision (200×). According to a cut-off score selected by ROC analysis, the cohort was dichotomized into a low (0-7 budding foci, 107 cases, 66.9%) and a high-grade budding group (8 or more budding foci, 53 cases, 33.1%). The inter-observer test showed a good reproducibility with 0.717 as the К value. High-grade budding was significantly associated with the presence of lymphovascular invasion (LVI) (P=0.001), larger tumor size (P=0.014), and worse clinical outcome (P<0.001). By immunohistochemical staining, budded cells at the margin displayed epithelial mesenchymal transition (EMT)-like molecular phenotype and decreased proliferative activity. Survival analyses revealed that tumor budding (HR 4.275, P<0.001) together with tumor size (HR 2.468, P=0.002), node status (HR 2.362, P<0.001), and LVI status (HR 1.910, P=0.035) was the independent prognostic factor in IDC-NOS. In conclusion, tumor budding is a reproducible, significant, and independent histopathological prognostic factor in IDC-NOS.