CD44 and breast carcinoma: To validate the importance of CD44-/CD24- cell frequency in delayed metastasis, the testing set of patients was analyzed and the metastatic rates of patients with a higher frequency of CD44-/CD24- cells were higher than those with a lower frequency of CD44-/CD24- cells in the tested molecular subtypes of breast cancers (22.73% vs. 8.89% for luminal; 50% vs. 18.42% for HER-2+; 41.67% vs. 15% for TNBC with high vs. low CD44-/CD24- cells; Figure 2A).