Neoadjuvant Trastuzumab-Based Chemotherapy and Pathologic Complete Response in HER2-Positive Breast Cancer; A Systematic Review

Abstract

Abstract Introduction: Breast cancer is a prevalent global disease, with higher incidence in developed countries and greater mortality rates in developing countries due to disparities in screening, diagnostics, and treatment access. Classification is based on histology and molecular markers, with hormone receptor status and HER2 expression guiding treatment decisions. Trastuzumab has significantly improved outcomes for HER2-positive breast cancer. A systematic review was conducted to evaluate the effectiveness of neoadjuvant chemotherapy and Trastuzumab in achieving pathological complete response (pCR). Methods: Nine clinical trials focusing on HER2-positive breast cancer patients undergoing neoadjuvant chemotherapy and Trastuzumab were included. Eligibility criteria encompassed non-metastatic operable, locally advanced, or inflammatory breast cancer cases with pCR as the primary or secondary endpoint. Trials employed various chemotherapy and targeted therapy regimens with different Trastuzumab dosages. The primary outcome of interest was the pCR rate, while other survival outcomes were not analyzed. Data extraction and outcome definitions followed specific criteria. Results: Out of 3,126 initially identified studies, only nine trials met the inclusion criteria. Selected trials were described in terms of design, patient numbers, disease staging, HER2 status, administered neoadjuvant chemotherapy and Trastuzumab regimens, and primary/secondary endpoints. Among 1,209 patients receiving neoadjuvant chemotherapy and Trastuzumab, the overall pCR rate was 42%. Detailed information on pCR rates, endpoints, and trial numbers was provided, noting slight variations in the definition of pCR. Conclusion: In conclusion, this systematic review demonstrated a 42% pCR rate with neoadjuvant chemotherapy and Trastuzumab in HER2-positive breast cancer