HER2 expression, gene amplification and chromosome 17 copy number in primary pancreatic adenocarcinoma, matastatic lymph node and metastasis

HER2 expression or gene amplification is crucial for performing targeted theraphy. We assessed p185^HER2 (p185) expression, HER2 amplification and copy number of chromosome 17 centromere (CEP17) in pancreatic adenocarcinoma (PAC). We analyzed 26 tumours at diagnosis, 21 metastatic lymph nodes (mLN) and 38 distant metastases (mTS) by immunohistochemistry and by FISH. p185 overexpression was shown in 4% of primary PAC, 6% of mLN and 29% of mTS. Amplification was found restricted to 10% of the mTS and increased CEP17 in 21% of mTS and 16% of mLN. Overexpression of p185 was present in all amplified cases but in only 36% of increased CEP17. In conclusion HER2 amplification and increased CEP17 were mainly related to mTS or mLN and increased CEP17 was not always linked to overexpression of p185.