HER2 Testing in Patients With Breast Cancer: Poor Correlation Between Weak Positivity by Immunohistochemistry and Gene Amplification by Fluorescence In Situ Hybridization

摘要: Objective To evaluate amplification of the HER-2/ neu gene by fluorescence in situ hybridization (FISH) tumors with weakly positive (2+) immunohistochemical staining. Methods A total 1556 breast tumor biopsy specimens were referred to Mayo Medical Laboratories, Rochester, Minn, for HER2 testing between August and December 2000. Immunohistochemical (IHC) analysis was performed use a diagnostic test assessment overexpression, HercepTest. The IHCstained slides interpreted scored on scale ranging from 0 3+ according Food Drug Administration-approved guidelines. All as 2+ also routinely evaluated FISH HER-2/neu DNA probe kit (PathVysion). Specimens determined be amplified if ratio signals chromosome 17 centromere (CEP17) higher than 2.0. Results Thirty-eight percent HercepTest 0, 35% 1+, 14% 2+, 13% 3+. Of 216 26 (12%) had high level amplification, 54 (25%) demonstrated duplication HER2, 4 (2%) deleted and/or CEP17, 123 (57%) no apparent anomaly, CEP17 nor single gain (aneusomy) CEP17. Conclusion We recommend that all result amplification. results both assays should considered before making decision antiHER2 therapy.