CDKN2A and breast cancer: The TNBC treatment is the most challenging within breast cancer for its higher aggressive feature and lack of molecular targets [53,54,55], although there are a large number of tumor suppressor genes encoding proteins that inhibit cell transformation in breast cancer, such as TP53, Rb1, PTEN, BRCA1/2, CDKN1B, CDKN2A, etc.