In situ hybridization analysis of invasive breast carcinomas with immunohistochemically negative Her-2 status (a national multicenter study)

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

Objective

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.

Materials and Methods

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.

Results

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).

Conclusion

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.

Immunohistochemical HER2 Status Evaluation in Breast Cancer Pathology Samples: A Multicenter, Parallel-Design Concordance Study

Objective

As patients with increased human epidermal growth factor receptor (HER2) overexpression are more likely to benefit from trastuzumab treatment, the accuracy of HER2 receptor status in breast cancer patients is significant for appropriate disease management. However, this assessment is not harmonized and results may be highly variable between centers. The aim of this study was to investigate the degree of interlaboratory variability in the results of HER2 expression reported by 5 participating centers and to assess the concordance between these centers and a reference laboratory.Materials and Methods: A total of 30 breast cancer samples were tested and scored for HER2 expression using immunohistochemical method in 5 centers from Turkey and in a reference laboratory from Netherlands (Academic Medical Center, Amsterdam). All the participating centers had an experience of more than 10 years regarding the HER2 testing. The results were compared both among the centers and with the reference laboratory.

Results

When the concordance of participating centers and the reference laboratory was evaluated regarding negative (0-1+), equivocal 2(+) and positive 3(+) classification of HER2 immunostaining, the highest concordance was found in Center-A, and the lowest in Center-C (Kendall's tau-b concordance coefficient 0.911 and 0.724, respectively). The concordance of the centers with reference laboratory was 80.0% both in equivocal and positive samples, while it increased up to 91.8% in negative samples.

Conclusions

This study showed that in general there is sufficiently good agreement between the reference laboratory and the participating centers for immunohistochemical HER2 assessment.