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Cytokines are proteins that act in the immune response and inflammation and have been associated with the development of some types of cancer, such as gastric cancer (GC). GC is a malignant neoplasm that ranks fifth in incidence and third in cancer-related mortality worldwide, making it a major public health issue. Recent studies have focused on the role these cytokines may play in GC associated with angiogenesis, metastasis, and chemoresistance, which are key factors that can affect carcinogenesis and tumor progression, quality, and patient survival. These inflammatory mediators can be regulated by epigenetic modifications such as DNA methylation, histone protein modification, and non-coding RNA, which results in the silencing or overexpression of key genes in GC, presenting different targets of action, either direct or mediated by modifications in key genes of cytokine-related signaling pathways. This review seeks insight into the relationship between cytokine-associated epigenetic regulation and its potential effects on the different stages of development and chemoresistance in GC.

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Background and Objective: Immune checkpoint inhibition has shed light on a new era in cancer therapy, and randomized clinical trials have demonstrated that a meaningful portion of the overall population of metastatic gastric cancer (GC) patients may derive clinical benefit from immunotherapy, which raises the relevance in identifying predictive biomarkers. Programmed cell death-ligand 1 (PD-L1) expression has demonstrated a significant association between level of expression and the magnitude of benefit derived from immune checkpoint inhibition in GC. Nevertheless, this biomarker shows several pitfalls that must be considered in the therapeutic decision to incorporate immune checkpoint inhibition as the standard of care of GC, such as spatial and temporal heterogeneity, interobserver variability, immunohistochemistry (IHC) assay, and influence by chemotherapy or radiation therapy. Methods: In the present comprehensive review, we revised the main studies regarding PD-L1 evaluation in GC. Key Content and Findings: Here we describe the molecular characteristics of the tumor microenvironment in GC, the obstacles in the interpretation of PD-L1 expression and present the data of the clinical trials that have evaluated the efficacy and safety of immune checkpoint inhibition and the association with the biomarker expression, both in first-line and later lines of therapy. Conclusions: From the emerging predictive biomarkers for immune checkpoint inhibition, PD-L1 has demonstrated a meaningful association between level of expression in tumor microenvironment and the magnitude of benefit derived from immune checkpoint inhibition in GC.

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Gastric cancer (GC) represents ~10% of the global cancer-related deaths, increasingly affecting the younger population in active stages of life. The high mortality of GC is due to late diagnosis, the presence of metastasis and drug resistance development. Additionally, current clinical markers do not guide the patient management adequately, thereby new and more reliable biomarkers and therapeutic targets are still needed for this disease. RNA-seq technology has allowed the discovery of new types of RNA transcripts including long non-coding RNAs (lncRNAs), which are able to regulate the gene/protein expression of many signaling pathways (e.g., the PI3K/AKT/mTOR pathway) in cancer cells by diverse molecular mechanisms. In addition, these lncRNAs might also be proposed as promising diagnostic or prognostic biomarkers or as potential therapeutic targets in GC. This review describes important topics about some lncRNAs that have been described as regulators of the PI3K/AKT/mTOR signaling pathway, and hence, their potential oncogenic role in the development of this malignancy.

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BACKGROUND: Gastric cancer remains one of the 3 most common causes of cancer death worldwide. Understanding the health and economic factors that affect screening cost-effectiveness in different countries will help address when and where it makes most sense to screen for gastric cancer. METHODS: We performed a cost-effectiveness analysis using a Markov model to compare screening and surveillance strategies for gastric cancer in Brazil, France, Japan, Nigeria, and the United States. Primary outcome was the incremental cost-effectiveness ratio. We then performed a sensitivity analysis to determine how each variable affected the overall model. RESULTS: In all countries, the most cost-effective strategies, measured by incremental cost-effectiveness ratio relative to no screening, were screening every 10 years, surveillance of high- and low-risk patients every 5 and 10 years, respectively, and screening every 5 years. Only Japan had at least one cost-effective screening strategy. The most important variables across different screening strategies and countries were starting age of screening, cost of endoscopy, and baseline probability of local gastric cancer at time of diagnosis. CONCLUSIONS: Our model suggests that screening for gastric cancer is cost-effective in countries with higher incidence and lower costs of screening, but screening may still be a viable option in high-risk populations within low incidence countries.

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JUSTIFICATION: The prevalence of gastric cancer (GC) with increased expression of the HER2 oncoprotein shows important variations worldwide. Incidence and mortality rates of GC in Costa Rica are among the highest in Latin America and the world; however, the prevalence of HER2-positive cases in this country is unknown. Evaluation of this parameter is important to decide the therapeutic approach for GC patients. The aim of this study was to provide an estimation of the prevalence of GC patients overexpressing the HER2 oncogene in Costa Rica. METHODS: The investigation was carried out in two phases. The first one consisted of a retrospective review of 331 clinical records of patients diagnosed with advanced or metastatic GC from January 2010 to January 2012 in four hospitals in Costa Rica. In the second phase, immunohistochemistry (IHC) and fluorescent in situ hybridisation (FISH) analyses were performed in formalin-fixed and paraffin-embedded (FFPE) surgical samples from 50 patients diagnosed with GC between 2012 and 2015. RESULTS: Of the 331 clinical files reviewed, the assessment of HER2 status was carried out in 62 patients (18.7%), of which only five (8%) were HER2-positive. In the 50 surgical specimens in which IHC and FISH analyses were performed, two of them (4%) presented overexpression and amplification of the HER2 oncogene. CONCLUSION: This study suggests that the prevalence of GC cases overexpressing the HER2 oncogene in Costa Rica is less than 8%. This is the first attempt ever undertaken to estimate the prevalence of HER2-positivity in GC in Costa Rica.

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Las lesiones precursoras de malignidad (gastritis crónica atrófica, metaplasia intestinal y displasia leve), según lo demuestran múltiples estudios, están claramente relacionadas con el riesgo que presentan como predictoras del cáncer gástrico y más aún en nuestra región considerada como de alto riesgo de esta patología. Se realizó un estudio prospectivo descriptivo con 212 pacientes entre 11 y 89 años de edad procedentes de la zona amarilla del departamento de Nariño, atendidos en el Centro de Investigaciones de Enfermedades Digestivas (CIED) del Centro Hospital La Rosa dependiente de la ESE Pasto Salud a quienes se tomaron 7 biopsias de mucosa gástrica sometidas a un procesamiento y coloración especial de Giemsa modificado para detectar lesiones precursoras de malignidad y presencia de Helicobacter Pylori. La prevalencia para gastritis crónica atrófica antrocorporal fue de 38,6%, metaplasia intestinal 24,4% y displasia leve 1,5%; presencia de infección para Helicobacter pylori en gastritis crónica atrófica 73,5%, para metaplasia intestinal 52% y displasia leve 100%; en relación a la severidad de las lesiones precursoras de malignidad de acuerdo a la escala de OLGA, 11,5% se clasificó como estadios III y IV; a excepción de un solo caso clínico todos fueron Helicobacter Pylori positivos. Se pone en consideración de la comunidad médica el protocolo del CIED para seguimiento y vigilancia de las lesiones precursoras de malignidad tratando de demostrar que la mayor estrategia sigue siendo la prevención para el control del cáncer gástrico en las regiones de alto riesgo.

Atrophic chronic gastritis (ACG), intestinal metaplasia (IM) and mild dysplasia (MD)) are all precursor lesions which have been clearly demonstrated by many studies to be related to risks for development of gastric cancer (GC). This is especially true in our region which is considered to be a high risk area for this disease. We conducted a prospective study of 212 patients between the ages of 11 and 89 years who were from the yellow zone of Nariño. Patients were cared for in the Centro de Investigaciones de Enfermedades Digestivas (CIED - Center for the Investigation of Digestive Diseases) at the Centro Hospital la Rosa which is part of the public health care system of Pasto. Seven gastric mucosa biopsies were taken from each subject and stained with specially modified Giemsa stain to detect precursor lesions and the presence of Helicobacter pylori. The prevalence of ACG was 38.6%, the prevalence of IM was 24.4%, and the prevalence of MD was 1.5%. Prevalence of H. pylori infections among patients with ACG was 73.5% while among patients with IM it was 52%, but prevalence rose to 100% among patients with MD. When severity of precursor lesions on the OLGA-staging (Operative Link for Gastritis Assessment) scale was 11.5%, lesions were classified as stage III and IV. With one exception, all of these patients were H. pylori positive. We would like to ask the medical community to consider CIED's Follow-up and Monitoring Protocol for precursor lesions in order to demonstrate that the best strategy continues to be GC prevention in high risk regions.

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