Comparison of immunohistochemistry, four in situ hybridization methods and quantitative polymerase chain reaction for the molecular diagnosis of HER2 status in gastric cancer: A study of 55 cases

Abstract

In the current study, the sensitivity and specificity of methods of HER2 status detection were studied in 55 patients presenting with gastric/gastroesophageal junction carcinoma (30 intestinal and 25 diffuse), in small biopsy (endoscopy; n=33) and resection specimens (n=22). The primary objective of the present study was to compare various methods for the assessment of HER2 status, with regards to the sensitivity and specificity of each method, as well as their concordance. In all cases, the status of HER2 was determined using immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), silver in situ hybridization (SISH), and quantitative polymerase chain reaction (qPCR). The concordance rate between IHC and ISH was 100% for IHC 0 and 3+. The concordance rate for IHC 1+ was 100% between IHC and SISH, and 92.9% between IHC and FISH. The concordance rate among different FISH methods was 100%, between FISH and SISH it was 96.2%, and between qPCR and ISH methods it was 88.5%. Thus, the results demonstrate that different in situ hybridization methods are comparable and that none were superior. Furthermore, the IHC and FISH methods were found to be comparable and the concordance rate was particularly good. qPCR analysis correlated well with the other methods and appears to be a possible alternative tool for detection of the HER2 status. However, the concordance rate of qPCR with other methods was identified to be lower in the diffuse carcinoma group of endoscopy biopsy specimens; therefore investigation of further cases is required.

HER2 Testing and Clinical Decision Making in Gastroesophageal Adenocarcinoma: Guideline From the College of American Pathologists, American Society for Clinical Pathology, and the American Society of Clinical Oncology

“…The FISH signals are often brighter and easier to count than are brightfield ISH signals. 97 Nevertheless, as stated previously, ISH and FISH results are generally concordant in GEA, 59,61,65,98,99 and either method is considered acceptable.…”

“…The other major brightfield ISH methods are chromogenic ISH and dual ISH, where a nonsilver chromogen alone is used or is used in combination with a silver chromogen on a separate probe to mark both HER2 and CEP17 on one slide. The authors of multiple studies 52, [59][60][61][62][63][64][65][66][67][68] agree that these various ISH methods are comparable and effective for GEA HER2 testing. There have been suggestions that brightfield ISH techniques have some advantages over FISH in that they can often be performed on automated stainers, do not require fluorescence microscopes, and allow for easier identification of tumor nuclei among normal tissues.…”

HER2 Testing and Clinical Decision Making in Gastroesophageal Adenocarcinoma: Guideline From the College of American Pathologists, American Society for Clinical Pathology, and American Society of Clinical Oncology

“…The other major brightfield ISH methods are chromogenic in situ hybridization and dual in situ hybridization, where either a nonsilver chromogen alone is used or is used in combination with a silver chromogen on a separate probe to mark both HER2 and CEP17 on 1 slide. The authors of multiple studies 52, [59][60][61][62][63][64][65][66][67][68] agree that these various ISH methods are comparable and effective for GEA HER2 testing. There have been suggestions that brightfield ISH techniques have some advantages over FISH in that they can often be performed on automated stainers, do not require fluorescence microscopes, and allow for easier identification of tumor nuclei among normal tissues.…”

Human epidermal growth factor receptor 2 (HER-2) status evaluation in advanced gastric cancer using immunohistochemistry versus silver in situ hybridization

“…To date, a number of studies have tested the diagnostic value of IHC in detecting HER-2 positivity in gastric cancer in reference to more sophisticated molecular methods [7,9,[16][17][18][19][20][21][22][23]. Most comprehensive data on the concordance between IHC and SISH methods comes from a recent meta-analysis, which included a total of 12,679 cases from 45 individual studies [7].…”