ALDH1A1 and cancer: In our cohort of 158 TNBC cases, the results of immunohistochemistry staining of ALDH1 revealed that tumor tissues from 55.7% of patients showed ALDH1 expression, which is similar to the rate reported by Ohi et al,[16] but differs from that seen by De Brot et al[17] Interestingly, in our study a majority of the ALDH1+ cases showed low levels of ALDH1 expression that presented as focal positive expression, which may be compatible with the idea that cancer stem cells represent only a minority of the tumor cell population.