The histopathological and molecular features of breast carcinoma with tumour budding—a systematic review and meta-analysis

Purpose Tumour budding (TB) is an adverse histological feature in many epithelial cancers. It is thought to represent epithelial–mesenchymal transition, a key step in the metastatic process. The significance of TB in breast carcinoma (BC) remains unclear. The aim of this study is to investigate the relationship between TB and other histological and molecular features of BC. Methods A systematic search was performed to identify studies that compared features of BC based on the presence or absence of high-grade TB. Dichotomous variables were pooled as odds ratios (OR) using the Der Simonian–Laird method. Quality assessment of the included studies was performed using the Newcastle–Ottawa scale (NOS). Results Seven studies with a total of 1040 patients (high-grade TB n = 519, 49.9%; low-grade/absent TB n = 521, 50.1%) were included. A moderate to high risk of bias was noted. The median NOS was 7 (range 6–8). High-grade TB was significantly associated with lymph node metastasis (OR 2.32, 95% c.i. 1.77 to 3.03, P