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Poster display session: Basic science, Endocrine tumours, Gastrointestinal tumours - colorectal & non-colorectal, Head and neck cancer (excluding thyroid), Melanoma and other skin tumours, Neuroendocrine tumours, Thyroid cancer, Tumour biology & pathology

4071 - Discordance between HER2 Expression status in Primary Tumor and Matched Malignant Ascites in Gastric Adenocarcinoma

Date

21 Oct 2018

Session

Poster display session: Basic science, Endocrine tumours, Gastrointestinal tumours - colorectal & non-colorectal, Head and neck cancer (excluding thyroid), Melanoma and other skin tumours, Neuroendocrine tumours, Thyroid cancer, Tumour biology & pathology

Topics

Translational Research

Tumour Site

Gastric Cancer

Presenters

Yaewon Yang

Citation

Annals of Oncology (2018) 29 (suppl_8): viii205-viii270. 10.1093/annonc/mdy282

Authors

Y. Yang1, H. Kim1, S. Son2, H.S. Han3

Author affiliations

  • 1 Department Of Internal Medicine, Chungbuk National University Hospital, 28644 - Cheongju-si/KR
  • 2 Department Of Pathology, Chungbuk National University Hospital, 28644 - Cheongju-si/KR
  • 3 Department Of Internal Medicine, Chungbuk National University, College of Medicine, 28644 - Cheongju-si/KR
More

Abstract 4071

Background

Test for the human epidermal growth factor receptor 2 (HER2) expression is an essential step to select gastric cancer patients for HER2 molecular targeted therapy. Peritoneal carcinomatosis with ascites is the most common manifestation of gastric cancer metastases, prevalence upto 40% in previous reports. The aim of this study is to compare the HER2 expression status in primary gastric adenocarcinoma and paired cell block of malignant ascites.

Methods

Forty-five patients with evaluable tissue samples of both primary gastric lesion and ascites cell block were enrolled. HER2 expression status was evaluated by immunohistochemistry (IHC) in primary tumor and in paired cell blocks of ascites which was confirmed by the qualified pathologist.

Results

HER2 expression was detected in 16 patients (35.6%) from primary gastric adenocarcinoma tissue and in 10 (22.2%) from ascites cell block. HER2 overexpression defined by IHC 3+ was observed in 2 (4.4%) and 3(6.7%) of primary lesion and ascites samples, respectively. However the HER2 status of primary tumor and ascites cell block showed discordance in all of those patients with HER2 overexpression. Patients with HER2 overexpression in primary gastric tissue showed HER2 negativity in ascites cell block, and vise versa. Of the 14 patients whom with two or more serial ascites samples, the HER2 IHC score differences between the samples were observed in five patients (35.7%).

Conclusions

Incidence of HER2 overexpression was slightly lower than previous reports in primary gastric tumor and metastatic ascites samples in this study. Discordances of HER2 expression status between the primary gastric adenocarcinoma and ascites cell block or between serially sampled ascites were observed in a significant proportion of the patients (20%). HER2 testing from both primary tumor and ascites cell block and from serial ascites sample could increase the sensitivity of HER2 overexpression detection, and assist to select adequate patients for HER2 molecular targeted therapy.

Clinical trial identification

Legal entity responsible for the study

Chungbuk National University Hospital.

Funding

Chungbuk National University Hospital.

Editorial Acknowledgement

Disclosure

All authors have declared no conflicts of interest.

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