Pathological Complete Response with Neoadjuvant Trastuzumab Combined with Chemotherapy in HER2 Positive Breast Cancer: A Single Institution Retrospective Analysis from Vietnam.

Purpose: Neoadjuvant regimens containing trastuzumab and chemotherapy were widely used in human epidermal growth factor 2 (HER2) positive breast cancer patients. In this article, we report complete pathological response (pCR) rates from a single institution in Vietnam.

Patients And Methods: Medical records of HER2 positive breast cancer patients who received neoadjuvant treatment with trastuzumab combined with chemotherapy were reviewed. Information on patient demographics, breast cancer stage, pathology reports, surgical data, and treatment regimens were collected. Pathological response was evaluated using Chevallier's criteria, in which complete pathological response was defined as yT0yN0 or yTisN0.

Results: Thirty-nine eligible breast cancer patients treated with chemo-trastuzumab combined regimens in a neoadjuvant setting at Vietnam National Cancer Hospital were included in the analysis. Median age was 47 (range 32-72 years). Of these 39 patients, 5 (12.8%) were at stage II and 34 (87.2%) were at stage III. Median tumor size was 5.8 cm. There were 22 (56.4%) and 17 (43.6%) patients who had hormone receptor (HR) negative and positive diseases, respectively. Pathological complete response in the breast was demonstrated in 30 out of 39 (76.9%) patients. Of 35 patients with lymph nodal involvement, axillary pCR occurred in 25 (71.4%) patients. Total pathological complete response (tpCR) was achieved in 25 (64.1%) of the evaluated patients. There was no significant association between pathological response rates and age, tumor grade, hormone receptor status, and Ki-67 expression.

Conclusion: Neoadjuvant treatment with trastuzumab and chemotherapy combined in patients with HER2 positive breast cancer yielded a pathological complete response rate of 64.1%.