CD44 and breast cancer: Based on these disparate findings, there are probably several factors that may affect the expression of these markers in human breast cancer, including the use of different antibodies and conditions for immunohistochemistry (Olsson et al, 2011; Resetkova et al, 2010; Almed et al, 2012) CSCs are responsible for the initiation, progression and recurrence of various types of cancers, including breast cancer; however, we didn’t find any significant association between CD44 expression and clinical outcomes in this study.