# Evaluating the Effectiveness of Neoadjuvant Therapy in Her2-Positive Invasive Breast Cancer: A Comprehensive Analysis of 167 Cases in Romania

## TL;DR

This study analyzed 167 Romanian patients with Her2-positive breast cancer and found a 50.29% success rate for neoadjuvant therapy, with certain factors linked to better outcomes.

## Contribution

The study is the largest of its kind in Romania and identifies pCR rates and predictors in Her2-positive breast cancer patients.

## Key findings

- A 50.29% pathological complete response (pCR) rate was observed in Her2-positive invasive breast cancer patients.
- Higher pCR rates were found in hormone-negative cases, Stage II cases, and cases with high Ki-67 values.
- The study confirms that pCR is a strong predictor of improved survival outcomes in Her2-positive breast cancer.

## Abstract

This study investigated treatment efficacy for 167 patients with invasive breast cancer. The treatment included chemotherapy and a targeted therapy for Her2-positive cancer. The overall success rate was 50.29%, meaning that in about half of patients the histopathological examination of resection specimens revealed a complete absence of invasive tumor cells in the breast tumor and the absence of tumor cell in the lymph nodes following therapy. The study identified some factors associated with a higher chance of therapy response. This study is the largest of its kind in Romania, and its results are similar to those of other studies on Her2-positive breast cancer.

Pathological complete response (pCR) following neoadjuvant therapy for IBC has shown a strong correlation with event-free survival and overall survival. Over the past three decades, the five-year net survival rate for breast cancer has generally increased; however, several Eastern European countries exhibit lower survival rates. Data from Romania, specifically regarding Her2-positive breast cancer response to therapy, are notably limited. Background/Objectives: The aim of our study was to evaluate the response to NAT using chemotherapy and Her2-targeted therapy in a cohort of 167 patients diagnosed with invasive breast cancer in our institution. Methods: We retrospectively analyzed 167 consecutive cases diagnosed with IBC in our institution between January 2020 and September 2024 with Stages II and III Her2-positive IBC. The overall pCR rates and several factors cited in the literature as predictors of pCR were analyzed. Results: Overall, the pCR rate was 50.29%, with higher values in 3+ cases (62.28%) compared to 2+ cases/ISH amplified (24.53%). Higher pCR rates were observed in hormone-negative cases, Stage II cases, estrogen receptor-negative cases, and high Ki-67 values. Patient age, ISH group, Her2 copy number, Her2:CEP17 ratio, and clinical lymph node involvement did not seem to influence pCR rates in our study. Conclusions: The data presented in our study represent, to the best of our knowledge, the largest cohort of patients diagnosed with Her2-positive IBC from Romania. The presented results and the pCR predictive factors were comparable to those cited in other studies on Her2-positive IBC cases.