Her2 Status in Gastric Adenocarcinoma: A Comparison of Immunohistochemistry (IHC), Fluorescent In-Situ Hybridization (FISH) and Dual Color Silver In-Situ Hybridization (SISH) Methods.
Chen Zhou, David Huntsman, Beverly Carter, Tom Thomson, Julie Lorette, Sylvia Lee, Lynda Bell, Francine Aubin, Ryan Woods, Howard Lim, Sharlene Gill. British Columbia Cancer Agency, University of British Columbia, Vancouver, Canada
Background: Testing of Her 2 status of gastric adenocarcinoma is now being requested as a routine pathology test as trastuzumab is a potential treatment option for Her2 positive gastric adenocarcinoma. However, reports about Her 2 testing in gastric adenocarcinoma are few and standards for Her2 testing in gastric adenocarcinoma are not yet established.
Design: A total of 87 patients with gastric adenocarcinoma either from the British Columbia Cancer Agency tumor registry or from an ongoing prospective clinical trial were identified. Formalin fixed biopsy or resection tissues containing gastric adenocarcinoma were used for IHC staining for Her2 protein expression (Ventana®,4B5 antibody), for FISH testing (Abbott, PathVysion®) and for dual color SISH testing (Ventana®, Inform Her2).
Results: When the ASCO/CAP guideline for Her2 testing in breast cancer is used, Her2 protein expression positive rate is 12.7% (IHC 3+, 7 cases; and IHC 2+ with gene amplification by FISH or SISH, 4 cases), Her2 gene amplification rate by FISH is 14.9% (13/87 cases) and by SISH is 13.8% (12/87 cases). When the modified ASCO/CAP guideline, as defined by the manufacturer's package insert is used, Her2 protein expression positive rate is 19.5% (IHC 3+, 11 cases; and IHC 2+ with gene amplification by FISH, 6 cases) or 18.4% (IHC 3+, 11 cases; and IHC 2+ with gene amplification by SISH, 5 cases), Her2 gene amplification rate by FISH is 18.4% (16/87 cases) and by SISH is also 18.4% (16/87 cases). There is good concordance between FISH and SISH, IHC and FISH and IHC and SISH (table 1).
|FISH vs. SISH||IHC vs. FISH||IHC vs. SISH|