Is There any Concordance between of IHC with FISH in HER2-Positive Breast Cancer Patients?

Background: In developed or developing countries, the most common cancer in women is breast cancer with a pick in 40-50 years in Asia. Herein, we compared the association between IHC with FISH in HER2-positive breast cancer patients and affection of trastuzumab on disease free survival and overall survival (OS). Subjects and Methods: Immunohistochemical (IHC) analysis of hormone receptors and HER2 was performed in 133 patients with breast cancer between 2003 and 2014. Patients were selected for Herceptin adjuvant treatment, according to IHC 3+ or FISH+. The specimens for pathology reports were fixed at 10% neutral-buffered formalin (pH=7.4) for 24 hours, then sliced into 4 μm sections. Results: The mean age of patients at diagnosis was 46.39 years (range, 24-78 years), 100% female. Concordance rates between IHC and FISH were 31.1% for IHC 2+ and 84.1% for IHC 3+ (p<0.001). The 87 patients had age ≤50 years and 46 patients had >50 years. Of the 133 patients, 30 patients (22.6%) had metastasis and 72 (54.1%) had right involvement. Ninety three (69.9%) patients had lymph node invasion. 48 patients (36.1%) were treated with trastuzumab and 85 (63.9%) were treated without trsastuzumab. The 10-year survival rate was 70% and the mean survival was 49 months. Conclusion: We recommend clinicians that FISH analysis is as a predictor in breast cancer patients with IHC score 2+. In contrast, FISH analysis of IHC 3+ samples was no useful. Trastuzumab therapy is effective and tolerated for breast cancer with IHC 3+ and probably IHC 2+/FISH+.