HER2 gene assessment in liquid biopsy of gastric and esophagogastric junction cancer patients qualified for surgery

• Published in: BMC gastroenterology 2020-11, Vol.20 (1), p.382-382, Article 382
• Main Authors: Grenda, Anna, Wojas-Krawczyk, Kamila, Skoczylas, Tomasz, Krawczyk, Paweł, Sierocińska-Sawa, Jadwiga, Wallner, Grzegorz, Milanowski, Janusz
• Format: Article
• Language: English
• Subjects: Biomarkers, Tumor; Biopsy; Copy number; Deoxyribonucleic acid; Diagnosis; DNA; DNA Copy Number Variations; ErbB-2 protein; Esophageal cancer; Esophagogastric cancer; Esophagogastric Junction; Fluorescence in situ hybridization; Gastric cancer; Gastroenterology; Gene Amplification; Genes, erbB-2; Genetic aspects; Genetic testing; Health aspects; HER2 copy number; HER2 receptor; Humans; Hybridization; Immunohistochemistry; In Situ Hybridization, Fluorescence; Liquid Biopsy; Metastasis; Methods; Paraffin; Patients; Proteins; Receptor, ErbB-2 - genetics; Statistical analysis; Stomach cancer; Stomach Neoplasms - genetics; Stomach Neoplasms - surgery; Surgery
• ISSN: 1471-230X; 1471-230X
• DOI: 10.1186/s12876-020-01531-5

Amplification of HER2 gene (ERBB2) and overexpression of HER2 protein on cancer cells are found in 10-26% of gastric cancer (GC) and esophagogastric junction cancer (EGJC). Gene copy number variation (CNV) could be detected in these patients in liquid biopsy and in cancer cells. We analysed HER2 gene CNV used qPCR method in 87 sera collected from GC and EGJC patients before surgical treatment and in 40 sera obtained from healthy donors. HER2 gene CNV was also assessed in formalin-fixed paraffin-embedded (FFPE) tumor tissue. Furthermore, we assessed the number of HER2 gene copies and HER2 expression in cancer cells using the fluorescent in situ hybridization method (FISH) and immunohistochemistry (IHC). We found that the HER2 gene copy number in liquid biopsy was higher in GC and EGJC patients compared to healthy people (p = 0.01). Moreover, EGJC patients had higher number of HER2 gene copies than healthy donors (p = 0.0016). HER2 CNV examination could distinguish healthy individuals and patients with gastric or esophagogastric junction cancers with sensitivity and specificity of 58% and 98% (AUC = 0.707, 95% CI 0.593-0.821, p = 0.004). We found that patients with a high copy number of the HER2 gene in the tumor tissue assessed by qPCR (but not by FISH) have significantly more often a high number of HER2 gene copies in liquid biopsy (p = 0.04). We suggested that HER2 testing in liquid biopsy could be used as an auxiliary method to analysis of HER2 status in tumor tissue in gastric or esophagogastric junction cancers.