Analysis of surrogate markers for target-specific therapy in breast carcinomas using archival materials

Recent development of target-specific therapy may have the potential to revolutionize cancer therapy. Target-specific therapy such as trastuzumab or imatinib requires the presence of its specific target in cancer cells. Therefore, it has become very important to identify these targets as a surrogate marker such as HER2/neu for trastuzumab in breast cancer or c-kit for imatinib in gastrointesitinal stromal tumor for these treatments to exert maximum clinical benefits on the patients with these malignancies. Archival or 10% formalin-fixed and paraffin-embedded materials could be the most accessible materials available for examining these surrogate markers for therapy, especially in patients with breast carcinoma. In addition, correlation of the findings with histological features that are pivotal in an evaluation of the findings obtained and retrospective analysis are both possible in these analyses. Immunohistochemistry or FISH for HER2/neu have been widely performed in numerous institutions and provide the gold standard for the treatment of trastuzumab in patients with breast carcinoma. In addition, an analysis of potential surrogate markers at DNA, mRNA and protein levels has become possible using archival materials of human breast carcinoma. However, it is very important to make these analyses widely available or possible to perform in any of the regular diagnostic laboratories without technical difficulties and financial burden on the patients. In addition, it is necessary to standardize the following when using surgical pathology materials for the analysis of these markers, especially in terms of quality control or reproducibility of the results obtained by the analysis: (1) fixation or specimens preparation, (2) methodology to be used and (3) interpretation and/or assessment of the findings.