2332P - Overall survival in breast cancer patients with HER2-low status single- center experience

Background

The HER2/neu (ERBB2) oncogene is amplified and/or overexpressed in approximately 15% of breast cancers (BC), and is a strong prognostic factor for relapse and poor overall survival (OS), particularly in node-positive patients. The aim of this study was to evaluate the prognostic significance of HER2-low status in BC. We also compared HER2-low subgroup with HER2-0 according to clinical, histopathological, laboratory and molecular factors.

Methods

The analysis included medical records of 657 BC patients treated in NIO in Gliwice in years 2002-2018. Human epidermal growth factor receptor 2 overexpression was assessed using an IHC method in postoperative specimens or samples obtained by thick needle biopsy. HER2 gene amplification was additionally assessed by FISH in HER2 (2+) cases.

Results

Median age of all women was 52 years (range from 24 to 81). 176 (27%) tumors were HER2-low BC, 248 (38%) HER2-0 and 233 (35%) HER2-positive tumors. There was no difference according to molecular factors such as BRCA gene mutation (p=0.780) or patient’s age (p=0.275) between patients with HER2-low tumors and HER2-0. No differences were also detected between the both groups according to family history of cancer, co-morbid condition, menopausal status, tumor size, lymph nodes with metastases (N+) or higher histologic tumor grade (G3). BC patients with HER2-low tumors more often had positive estrogen receptor status (ER+) (80% vs. 60%, p=0. 0001). There was no reported differences according to OS between patients with HER2-low status and HER2-0 (p=0.747). In subgroup of patients with ER-negative receptor status (ER-) OS were insignificantly worse in patients with HER2-low status in comparison to HER2-0 (5-year OS 72.6% vs. 86.7%, p=0.074). There was also observed tendency to worse OS in patients with HER2-low status in subgroups with higher T3-4 (61.2% vs. 75.1%, p=0.217), G3 (80.7% vs. 89.2%, p=0.139) and N+ (81.3% vs. 86.9%, p=0.599).

Conclusions

There was no association between HER2 status (HER2-low vs. HER2-0) and BRCA gene mutation, tumor size, the presence of metastases in lymph nodes and G. HER2-low status worsens OS in subgroups of patients with negative prognostic factors in comparison to patients with HER2-0.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Maria Sklodowska-Curie National Research Institute of Oncology Gliwice Branch.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.