Joseph C, et al. - Researchers evaluated the prognostic value of CD133 expression (a cancer stem cell marker associated with cancer progression and patient outcome) in early invasive breast cancer (BC) using the METABRIC cohort (Molecular taxonomy of breast cancer international consortium) and a large well-characterised BC cohort. They reported characteristics of poor prognosis including high tumour grade, larger tumour size, high Nottingham Prognostic Index, HER2 (human epidermal growth factor receptor 2) positivity and hormonal receptor negativity, in relation to high expression of CD133 either in mRNA or protein levels. A positive association of high CD133 expression with proliferation biomarkers including p16, Cyclin E and Ki67, was also observed. Other stem cell markers including CD24, CD44, SOX10, ALDHA3 and ITGA6 were highly expressed on tumours expressing CD133. CD133 protein expression was identified as an independent risk factor for shorter BC-specific survival in multivariate analysis. Findings demonstrated the prognostic value of CD133 in invasive BC.