Discordances in HER2 status between primary gastric cancer and corresponding metastatic sites

作者：Gumusay Ozge^*; Benekli Mustafa; Ekinci Ozgur; Baykara Meltem; Ozet Ahmet; Coskun Ugur; Demirci Umut; Uner Aytug; Dursun Ayse; Atak Ecine Yesim; Buyukberber Suleyman

来源：Japanese Journal of Clinical Oncology, 2015, 45(5): 416-421.

DOI：10.1093/jjco/hyv020

• HER2
• gastric cancer
• discordance
• IHC
• SISH

Objective: Determination of human epidermal growth factor receptor-2 status in advanced gastric cancer is important in clinical decision making. In the trastuzumab for GC trial, trastuzumab-based therapy demonstrated a significant overall survival benefit in patients with human epidermal growth factor receptor-2-positive advanced gastric cancer. Human epidermal growth factor receptor-2 discordance in gastric cancer primary and its metastases has been long debated. The aim of the study was to evaluate the rate of human epidermal growth factor receptor-2 discordance and its effect on treatment decisions in advanced gastric cancer.
Methods: A total of 74 patients with advanced gastric cancer were included in the study. Both immunohistochemical staining and dual-color silver in situ hybridization were performed in all patients to evaluate the human epidermal growth factor receptor-2 status of the primary lesion and paired metastasis.
Results: The assessment of human epidermal growth factor receptor-2 status with the immunohistochemical staining method and dual-color silver in situ hybridization revealed a discordance rate of 9.5 and 16.2%, respectively. However, this discordance was clinically meaningful in only one patient leading to a change in treatment decision. While this patient had a human epidermal growth factor receptor-2-negative status in primary tumor (immunohistochemical = 0, dual-color silver in situ hybridization = negative), the human epidermal growth factor receptor-2 status was positive for liver metastasis (immunohistochemical = 2+, dual-color silver in situ hybridization = positive). Trastuzumab was added to the chemotherapy regimen.
Conclusions: In this study, we found a higher rate of human epidermal growth factor receptor-2 discordance between primary gastric tumor and metastatic lesions compared with the rates reported in previous studies. Detection of a human epidermal growth factor receptor-2-positive metastasis with a human epidermal growth factor receptor-2-negative primary tumor suggests that investigation of human epidermal growth factor receptor-2 is also required for the metastatic lesion and that trastuzumab could be administered in the case of a positive result.

• 出版日期2015-5