CCNB1 and neoplasm: In both cohorts, a significant association was observed between high CCNB1 mRNA expression and the presence of LVI (all; p < 0.0001) and other features characteristic of aggressive tumour behaviour, including large tumour size, high histological grade, hormonal receptor negativity (all; p < 0.0001) and HER2 positivity (p < 0.0001 in METABRIC and p = 0.006 in TCGA).