A Firm 2 to 3 Cm Mass Is Palpable in the Upper

A firm 2 to 3 cm mass is palpable in the upper outer quadrant of the right breast of a 52-year-old woman. There are no palpable axillary lymph nodes. A lumpectomy with axillary node dissection is performed and the breast lesion is found to have positive immunohistochemical staining for HER2/neu (c-erb B2) . Staining for oestrogen and progesterone receptors is negative. Which of the following additional treatment options is most appropriate, based upon these findings?

A) Radical mastectomy
B) St John's wort
C) Tamoxifen
D) Trastuzumab
E) Vancomycin