The best example of studies confirming the effectiveness of adjuvant trastuzumab therapy in patients with early HER2-positive breast cancer are 4 international randomized trials-HERA, NSABP-B31, NCCTG-N98 and BCIRG 00, of which the HERA study became a registration study in the above indication [90,91,92,93,94]. This evidence concerns the gene ERAL1 and breast carcinoma.