Background/aim: The aim of the present study was to compare human epidermal growth factor receptor 2 (HER2) expression before and after trastuzumab-based chemotherapy in patients with advanced HER2-positive gastric cancer.
Materials and methods: We assessed HER2 expression using immunohistochemistry and/or fluorescence in situ hybridization in pre-treatment biopsied specimens and post-treatment resected specimens obtained from seven patients with advanced HER2-positive gastric cancer receiving trastuzumab-based chemotherapy.
Results: Four patients maintained the HER2-positive status and three patients had a change in HER2 expression from positive to negative. In patients showing the loss of HER2 expression after treatments, HER2-positive tumor cells with a dominant histological type disappeared, and HER2-negative tumor cells with another dominant histological type were identified.
Conclusion: HER2 expression can change after trastuzumab-based chemotherapy in patients with advanced HER2-positive gastric cancer. Continuous monitoring of HER2 expression after treatments may be utilized to determine whether the continued use of trastuzumab is advisable.
Keywords: HER2; advanced gastric cancer; chemotherapy; trastuzumab.
Copyright© 2020, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.