Objective: The aim of the study is to evaluate HER-2 gene amplification ratio in c-erbB-2 score 2 breast carcinoma cases which have been controversial for targeted terapy and determinate its correlation with pathologic prognostic factors.

Material and Method: We analyzed 80 infiltrating breast carcinomas, which were immunohistochemically score 2 with silver in situ hybridization (SISH) assay to determine Her-2 gene amplification. Afterwards cases have been grouped as amplification positive (AP) and amplification negative (AN). These groups have been compared with each other to reveal their relationship with pathologic prognostic factors.

Results: 30% of the cases showed HER-2 gene amplification with SISH. Median age of patients in AP group was 50.3 (±11.4). Median age of AN group was 56.7 (±13.0). We found that tumors in AP group had much higher mitotic rate (p= 0.044). Mean metastatic lenf node number in AP group was 10, while it was only 1 in AN group. Lenfovascular invasion was the other striking parameter which showed statisticaly significant correlation with HER-2 amplification. We didn't find any statisticaly significant correlation between HER-2 amplification and tumor size, histologic grade, nuclear grade, diameter of the largest metastatic lenf node, steroid receptor expression and tumor necrosis.

Conclusion: Tumors that show HER-2 gene amplification have much higher mitotic rate, increased metastatic lenf node number and increased lenfovascular invasion rate. Unignorable part of controversial immunohistochemically c-erbB-2 score 2 cases show HER-2 gene amplification and we need to confirm these cases with genetic tests. SISH is a cheap, easy and cantitative alternative.