It has been reported that ER, PR, and HER-2 are negative in more than 90% of MBC, which is similar to the biological characteristics of triple-negative breast cancer (TNBC) [22], while at least one of keratin, including AE1/3, CK7, CK5, CK14, and CK15, is positive. This evidence concerns the gene KRT15 and triple-negative breast carcinoma.