Effect of neoadjuvant chemotherapy on HER-2 expression in surgically treated gastric and oesophagogastric junction carcinoma: a multicentre Italian study

Predictors of response to neoadjuvant chemotherapy are not available for gastric and oesophago-gastric junction carcinoma. HER-2 over-expression in breast cancer correlates with poor prognosis and high incidence of recurrence. First aim of this study was to evaluate if the HER-2 expression/amplification is predictive of response to neoadjuvant chemotherapy in terms of pathologic regression. Secondary aim was to evaluate if HER-2 expression varies after neoadjuvant treatment. Thirty-five patients with locally advanced gastric or oesophago-gastric junction carcinoma underwent preoperative chemotherapy and surgical resection at San Raffaele Scientific Institute and Spedali Civili of Brescia. HER-2 expression/amplification was evaluated on every biopsy at diagnosis time and on every surgical sample after neoadjuvant chemotherapy. Pathologic response to chemotherapy was evaluated according to TNM classification (ypT status and ypN status) and Mandard’s tumour regression grade classification. In our series 10 patients (28.6%) showed a reduction in HER-2 overexpression and in 6 of them (17.1%) HER-2 expression completely disappeared. Only three of the six patients with HER-2 disappearance had a complete pathological response to neoadjuvant chemotherapy. There was a strong correlation between HER-2 negativity on biopsy and absence of lymph node metastasis in surgical samples after neoadjuvant chemotherapy, irrespective of nodal status before chemotherapy. A direct correlation between HER-2 reduction after neoadjuvant chemotherapy and pathologic regression (primary tumour and lymph nodes) in surgical samples was found. HER-2 negativity may represent a predictor of pathologic response to neoadjuvant chemotherapy for gastric and oesophago-gastric junction adenocarcinoma. Neoadjuvant treatment can reduce HER-2 overexpression.