To further examine the physiological relevance of HER2-STAT3-survivin regulation in radiotherapy resistance of HER2-positive breast cancers, we evaluated the expression level of phosphorylated STAT3 (Tyr705), STAT3, and survivin in relapsed (non-responder group; n = 7) or recurrence-free (responder group; n = 8) HER2-positive breast cancer patients after radiotherapy. Here, ERBB2 is linked to breast carcinoma.