[Comparison of HER2 immunohistochemical results for advanced gastric cancer obtained on using 3 different antibodies]

We compared the results of immunohistochemical assessment of HER2 expression in 107 samples of advanced gastric cancer on using 3 currently used antibodies. Expression was scored as 0 to 3+, and equivocal or discordant cases were subjected to fluorescence in situ hybridization(FISH)analysis. HER2 scores of 2+or 3+were noted in 16.8% of cases(18/ 107)using SV2-61g, in 29.9% of cases(32/107)using Dako HercepTest, and in 34.6% of cases(37/107)using 4B5. The results of the HER2 test differed according to the antibodies used for immunohistochemistry preceding FISH analysis, and the HER2 positive rates after the FISH analysis were 14.0%(15/107)using SV2-61g, 19.6% (21/107)using Dako HercepTest, and 22.4% (24/107)using 4B5. Thus, therapeutic decisions might be considerably influenced by the antibody used for the HER2 test.