Role of Metformin in Combination with Trastuzumab and Neoadjuvant Chemotherapy in Treatment of HER-2 Positive Breast Cancer

Abstract

Backgound: HER2 overexpression is a good predictive marker of HER2 targeted therapy, which means that HER2 therapy will be very effective in reducing the size of HER2 positive breast cancers. Therefore, the size of HER2 positive breast cancer can easily be reduced in patients who wish to have a breast-conserving operation, and potentially improves the outcome of patients if pathologic complete response (PCR) can be achieved. Objective: To determine whether metformin use with trastuzumab was associated with improvement in PCR rate in patients with breast cancer receiving neoadjuvant chemotherapy. Patients and Methods: This prospective study was conducted at the Clinical Oncology Department, Aswan University and Upper Egypt Hospitals in the period between 1/7/2016 and 1/9/2019. This study included 30 patients divided into 2 groups, test group (metformin group) and standard group (non-metformin group). Histopathology was confirmed by tissue core biopsy. Results: All patients in the two groups in our study achieved either pathological complete response or partial response. No patients developed disease progression or were still stable disease. Among the patients in test group (metformin group), 12 patients (80%) achieved pathological complete response (PCR) while 3 (20%) patients did not achieve PCR. However, among the patients in standerd group (non-metformin group) 9 patients (60%) achieved pathological complete response (PCR) while 6 (40%) patients did not achieve PCR. There was statistically significant difference between the two groups regarding the response with better PCR in metformin group (p value is 0.089). Conclusion: The addition of metformin to tratuzumab in neoadjuvant chemotherapy has a significant impact on pathological complete response (PCR) in female patients with HER-2 positive breast cancer.