The Evaluation of HER-2 Status with Immunohistochemical and Molecular Analyses In Breast Carcinomas

OBJECTIVE

Patients with human epidermal growth factor receptor-2 (HER-2) + breast cancer are eligible for trastuzumab treatment; therefore, accurate assessment of HER2 status is essential. Immunohistochemistry and in situ hybridisation are currently the most commonly used methods to assess HER2 status. Polimerase chain reaction-based assays allow quantitative determination of HER2 amplification or overexpression, but are not routinely used. We evaluated the relevance of immunohistochemistry, chromogenic in situ hybridisation and real time-polimerase chain reaction for HER2 status determination.

METHODS

We analysed 76 primary breast carcinomas. Blocks of tumours with >10% in situ component were excluded from this study. Haematoxylin–eosin stainings, immunohistochemical stainings and in situ hybridisation techniques were performed on formalin-fixed paraffin-embedded tissue samples. Real time-polimerase chain reaction was performed on RNA extracted from tumour tissue with invazive carcinoma.

RESULTS

We observed statisticaly significant correlation between chromogenic in situ hybridisation and real time-polimerase chain reaction in immunohistochemically 0/1+ and 3+ cases. But, both in situ hybridisation and real time-polimerase chain reaction was heterogen in immunohistochemically 3+ cases.

CONCLUSION

Real time-polimerase chain reaction and immunohistochemistry are highly concordant methods for HER2 status assessment, and concordance was also highly chromogenic in situ hybridisation and immunohistochemistry. Real time-polimerase chain reaction allows a highly reliable quantitative assessment and could be a useful adjunct to immunohistochemistry as a new method.