According to the Student’s t-test, the mutational profile of PR− Luminal breast cancers was significantly different to that of PR+ tumors (p < 10−5), with 16 mutations being restricted to the ER+/PR− group, including mutations in ARID1A, ATR, BCL6, BRAF, CARD11, CDH1, AXIN2, GATA3, MUC16, CCDC82, RUNX1, and TBX3 (Table 2). This evidence concerns the gene RUNX1 and breast cancer.