OBJECTIVETo investigate the advantages and disadvantages of dual-color silver-enhanced in-situ hybridization (DSISH) and fluorescence in-situ hybridization (FISH) for determination of HER2 gene status in gastric carcinoma and to evaluate the feasibility of DSISH.

METHODSEighty cases of primary gastric or gastroesophageal junction adenocarcinomas diagnosed and treated surgically from January to March, 2009 at the West China Hospital were enrolled in the study. Automated immunohistochemistry (IHC) staining, FISH and automated DSISH were carried out to detect the HER2 status, respectively, and the concordance of the three techniques was then evaluated.

RESULTSDSISH and FISH failed initially, but repeated detection was successful in 5 cases. Gene amplification was detected in 12/13 IHC 3+ cases in DSISH and in 11/13 IHC 3+ cases in FISH. In 6 IHC 2+ cases, the amplification rate was both 1/6; in 18 IHC 1+ cases, the amplification rate was both 2/18. No amplification was observed in 43 IHC 0 cases. Only one of the 80 cases showed discrepancy, and therefore the overall concordance between FISH and DSISH was 98.8% (κ = 0.958, P < 0.01).

CONCLUSIONSDSISH represents a novel approach for the determination of HER2 status in gastric carcinoma, and the overall concordance between DSISH and FISH is excellent. Despite their advantages and disadvantages, DSISH is more feasible and practical for routine application in surgical pathology.