ALDH1A1 and neoplasm: In a report produced by Lee and his colleges, a higher proportion of CD44+/CD24− tumour cells and ALDH1 positivity in prechemotherapy tissues of 92 breast cancer patients was correlated with higher histologic grade, oestrogen receptor (ER) negativity, high Ki-67 proliferation index, and the basal-like subtype of breast cancer [29].