Trastuzumab for small HER-2+ breast cancer: small tumor, big decision

A 53-year-old postmenopausal woman was found to have a new area of microcalcification at the 10 o'clock position of her right breast during a routine screening mammogram. Ultrasound-guided core biopsy revealed a grade 2 invasive ductal carcinoma, estrogen receptor (ER)+ (90%), progesterone receptor positive (20%), and human epidermal growth factor receptor (HER)-2+ (3+ by immunohistochemistry). A right breast lumpectomy and sentinel node biopsy were performed. The invasive tumor measured 0.7 cm, no lymphovascular space invasion was identified, surgical margins were uninvolved, and the sentinel lymph nodes were negative for tumor. She was evaluated postoperatively in the medical oncology clinic to discuss an adjuvant treatment strategy. The question for our colleagues is: should she be offered adjuvant chemotherapy and trastuzumab prior to adjuvant radiation and 5 years of hormonal therapy?