HER-2/Neu and Hormone Receptor Analysis in Breast Carcinomas and Their Association with Clinicopathologic Parameters

Invasive breast carcinomas of no special type (IC-NST) are the heterogeneous tumours showing distinct prognostic features even in patients with similar clinicopathological characteristics. To date, many clinicopathological data have been analyzed to make a guess about prognosis and to determine treatment modality. In this study, HER-2/neu status was analyzed by using both immunohistochemical (IHC) and fluorescence in situ hybridization (FISH) methods, and its correlations with hormone receptor status and clinicopathological parameters were investigated.

The study was included 112 female patients with diagnosis of IC-NST. FISH for HER-2/neu was applied in only primary tumour tissues, while IHC analyses for HER-2/neu, estrogen (ER) and progesterone receptors (PR) were applied on both primary and metastatic lymph node foci. The results were compared with appropriate statistical methods.

Our rates of HER-2/neu overexpression and gene amplification in the overall study group were 22.3 and 25%, respectively. In the metastatic group, these rates were higher than those of the overall study group (34% and 40%, respectively). Gene amplification rate of the axilla positive group was 40%, while this rate in non-metastatic group was 6.7% (p=0.015). Overexpression and amplification results were compliant (χ²=77,591, p<0.001). The concordance rates in HER-2/neu negative and overexpression groups were 95.3% and 88%, respectively. Our false negativity rate was 4.7%. While 36% of score 3+ cases were ER positive, 67.1% of HER-2/neu negative cases showed ER positivity (p=0.01). The increase of gene amplification rate in ER negative cases over 50 years age was more than two times and statistically significant (p=0.014).

The concordance rates between the results of IHC and FISH in the HER-2 negative and the overexpression categories were compatible with the literature and lower than the literature, respectively. In the case of ER negativity, the patient's age over 50 years was associated with a higher rate of gene amplification.