HER2 based expression subpopulations in TNBC: pathological aspects and clinical significance

Background

Triple negative breast cancer (TNBC) is defined as hormone receptors less than 1% and human epithelial growth factor receptor 2 (HER2) negative by immunofluorescence. HER2 negative tumors can express an intracellular domain and present a HER2 positive phenotype. Before Trastuzumab era, the prognostic was worse in HER2 over expressed early breast cancer than in triple negative counterpart.

Methods

We conducted a retrospective analysis in order to explore the clinical significance of different degrees of tumor HER2 immunohistochemistry expression: 0, 1 or 2 inside triple breast cancer population.

Results

We analysed data from 440 early stage breast cancer patients, primary treated by surgery, addressed to the Department of Medical Oncology of University Hospital of Lille France, for adjuvant chemotherapy, between January 2010 and April 2013. 47 patients (10, 6%) had triple negative phenotype, 67pts (15,2%) HER2 positive, 326 pts (74, 1%) luminal. The mean age was 47 years, 19 %( 9pts) and deleterious BRCA1 or BRCA2 mutations were found in 10 pts (21%). The patients were more likely to have stage IIA 48 %( 23pts), invasive ductal carcinoma 74 %( 35pts), the surgery was conservatory in 28 pts(59,5pts)and the majority, 44pts (93%) was anthracycline exposed. The distribution of HER2 score among TN patients were as follows: 62% (29pts) negative, 27,6 %( 13pts) one plus, 10,4 %( 5pts) two plus and negative for in situ hybridization. HER 2 positivity correlated with pT (p = 0, 05), Ki67 (p = 0, 06) and tumor grade (p = 0, 08). Pathologic stage pT, Ki67, and HER2 score were associated with relapse (p 

Conclusions

The proportion of HER2 positivity inside TNBC population is valuable. The HER2 score 2 correlates with prognostic negative tumor features and associates with poor outcome in our analysis.

Clinical trial identification

Legal entity responsible for the study

University Hospital of Lille France

Funding

University Hospital of Lille France

Disclosure

All authors have declared no conflicts of interest.