Pathologic Complete Response in HER2-Positive Breast Cancer Patients Receiving Trastuzumab in Neoadjuvant Setting.

OBJECTIVE: To compare the pathological complete response in human epidermal growth factor receptor type 2 (HER-2) positive breast cancer patients getting neoadjuvant chemotherapy with or without trastuzumab.

STUDY DESIGN: Retrospective randomised double-arm observational study.

PLACE AND DURATION OF STUDY: Shaukat Khanum Memorial Cancer Hospital and Research Centre, Lahore, from 2008 to 2016.

METHODOLOGY: HER2-positive, lymph node positive, breast cancer patients receiving neoadjuvant chemotherapy (NACT) were retrospectively observed. Patients getting neoadjuvant trastuzumab, fulfilling the inclusion criteria were studied. The comparison group included randomly selected equal number of HER2-positive breast cancer patients having similar tumor characteristics, getting NACT only. Pathological complete response (pCR) was defined as no residual invasive or in situ residual tumor in breast tissue, or in the lymph nodes. One hundred and fifty-six patients were studied. Eighty-nine patients with HER2-positive disease received trastuzumab preoperatively. Sixty-four (n=64) patients received the complete standard dose of neoadjuvant trastuzumab along with chemotherapy. Almost equal number of patients (n=67) with HER2- positive disease were selected by random assortment for the reference group who did not receive trastuzumab before surgery.

RESULTS: The pathological complete response of study group was (n=32) 50%, which was 26.1% higher than the reference group (n=16) 23.9%; and this difference was statistically significant with a p-value of 0.002 (<0.05). The overall pCR was 36.6% (n=48).

CONCLUSION: Addition of trastuzumab to neoadjuvant chemotherapy doubled the pCR in HER2-positive breast cancer. Targeted therapy should be offered to all eligible patients with HER2-overexpressing breast cancer.