[HER2 testing for advanced recurrent gastric cancer in a general hospital]

The Japanese gastric cancer treatment guidelines(published as a web supplement for version 3)recommend the implementation of HER2 testing prior to the selection of chemotherapy. Since we had not yet implemented HER2 immunohistochemistry(IHC)methods for gastric cancer, we tried to compare the HER2 testing results from a reference laboratory(ref lab) and our hospital(in-house). The HER2 concordance rates were calculated between the results from in-house and ref lab using 26 cases(31 samples)which were from patients with advanced, metastatic unresectable, or Stage IV resectable gastric cancer. The HER2 expression(in-house/ref lab)was distributed as follows: negative/negative, 18 cases; negative/equivocal, 2 cases; negative/positive, 1 case;equivocal/equivocal, 2 cases; and positive/positive, 3 cases. The concordance rate was 88. 4%(23/26), and the mismatch rate was 11. 6%(3/26)between in-house and ref lab. Although IHC test results with in-house and ref lab had been generally consistent, it is still necessary to improve and standardize diagnostic accuracy in the near future.