Anti-HER2 monoclonal antibody trastuzumab improves the survival of those patients with advanced gastroesophageal adenocarcinoma (GEA) exhibiting HER2/ERBB2 overexpression/amplification. The current gold standard methods used to diagnose the HER2 status in GEA are immunohistochemistry (IHC) and silver or fluorescence in situ hybridization (SISH or FISH). However, they do not permit spatial and temporal tumor monitoring, nor do they overcome intra-cancer heterogeneity. Droplet digital PCR (ddPCR) was used to implement the assessment of HER2 status in formalin-fixed paraffin-embedded (FFPE) tumor DNA from a retrospective cohort (86 patients) and in cell-free DNA (cfDNA) samples from a prospective cohort (28 patients). In comparison to IHC/SISH, ddPCR assay revealed ERBB2 amplification in a larger patient fraction, including HER2 2+ and 0–1+ of the retrospective cohort (45.3% vs. 15.1%). In addition, a considerable number of HER2 2+ and 0–1+ prospective patients who were negative in FFPE by both IHC/SISH and ddPCR, showed ERBB2 amplification in the cfDNA collected just before surgery. cfDNA analysis in a few longitudinal cases revealed an increasing ERBB2 trend at progression. In conclusion, ddPCR in liquid biopsy may improve the detection rate of HER2 positive patients, preventing those patients who could benefit from targeted therapy from being incorrectly excluded.

Early detection of gastric cancer is remaining a challenge. This review summarizes current knowledge on non-invasive methods that could be used for the purpose. The role of traditional cancer markers such as CEA, CA 72-4, CA 19-9, CA 15-3, and CA 12-5 lies mainly in therapy monitoring than early detection. Most extensive studied biomarkers (pepsinogens, ABC method) are aiming at the detection of precancerous lesions with modest sensitivity for cancer. Tests based on the detection of cancer-specific methylation patterns (PanSeer), circulating proteins and mutations in circulating tumour DNA (CancerSEEK), as well as miRNA panels have demonstrated promising results bringing those closer to practice. More extensive research is required before tests based on the detection of circulating tumour cells, extracellular vesicles and cell-free RNA could reach the practice. Detection of volatile organic compounds in the human breath is a promising development; sensor technologies for this purpose could be very attractive in screening settings.

Purpose: The identification of HER2 overexpression in a subset of gastric adenocarcinoma (GA) patients represents a significant step forward in unveiling the molecular complexity of this disease. The predictive and prognostic value of HER2 amplification in advanced HER2 inhibitor-treated GA patients has been investigated. However, its predictive value in resectable patients remains elusive. Methods: We enrolled 98 treatment-naïve resectable Chinese GA patients with HER2 overexpression assessed using IHC. Capture-based targeted sequencing using a panel consisting of 41 gastrointestinal cancer-related genes was performed on tumor tissues. Furthermore, we also investigated the correlation between HER2 copy number (CN) and survival outcomes. Results: Of the 98 HER2-overexpressed patients, 90 had HER2 CN amplification assessed using next-generation sequencing, achieving 92% concordance. The most commonly seen concurrent mutations were occurring in TP53, EGFR and PIK3CA. We found HER2 CN as a continuous variable was an independent predictor associated with DFS (p = 0.029). Our study revealed HER2 CN-high patients showed a trend of intestinal-type GA predominant (p = 0.075) and older age (p = 0.07). The median HER2 CN was 15.34, which was used to divide the cohort into CN-high and CN-low groups. Patients with high HER2 CN had a significantly shorter DFS than patients with low HER2 CN (p = 0.002). Furthermore, HER2 CN as a categorical variable was also an independent predictor associated with DFS in patients. Conclusion: We elucidated the mutation spectrum of HER2-positive resectable Chinese GA patients and the association between HER2 CN and DFS. Our work revealed HER2 CN as an independent risk factor predicted unfavorable prognosis in HER2-positive GA patients and allowed us to further stratify HER2-positive resectable GA patients for disease management.

Precision medicine is already a reality in the field of oncology given that the selection and use of biomarker-driven therapies has clearly improved patient survival. Furthermore, a new, minimally invasive strategy termed ‘liquid biopsy’ (LB) has revolutionized the field by allowing comprehensive cancer genomic profiling through the analysis of circulating tumor DNA (ctDNA) released into the bloodstream. However, its detection requires extremely sensitive and efficient technologies. A powerful molecular tool based on the principle of ‘divide and conquer’ has emerged to solve this problem. Thus, digital PCR (dPCR) allows absolute and accurate quantification of target molecules. : In this review we will discuss the fundamentals of dPCR and the most common approaches used for partition of samples and quantification. The advantages and limitations of dPCR will be mentioned in the context of the field of LB in oncology. In our opinion, dPCR has proven to be one of the most sensitive methods available for LB analysis, even though some aspects such as its capacity of multiplexing and protocol standardization still require further improvements. Furthermore, the increasing sensitivities and lower costs of next generation sequencing (NGS) methods position dPCR as a confirmatory and complementary technique for NGS results which will likely prove very useful for treatment monitoring and assessing minimal residual disease.

Gastric cancer (GC) is a deadly disease with poor prognosis that is characterized by heterogeneity. New classifications based on histologic features, genotypes, and molecular phenotypes, for example, the Cancer Genome Atlas subtypes and those by the Asian Cancer Research Group, help understand the carcinogenic differences in GC and have led to the identification of an Epstein–Barr virus (EBV)-related GC subtype (EBVaGC), providing new indications for tailored treatment and prognostic factors. This article provides a review of the features of EBVaGC and an update on the latest insights from EBV-related research with a particular focus on the strict interaction between EBV infection and the gastric tumor environment, including the host immune response. This information may help increase our knowledge of EBVaGC pathogenesis and the mechanisms that sustain the immune response of patients since this mechanism has been demonstrated to offer a survival advantage in a proportion of patients with GC.

Background: 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. Methods: 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). Results: 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). Conclusions: 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.