Gastric cancer (GC) is the second most common cancer and first leading cause of cancer-related deaths in Peru. Infection by Helicobacter pylori (HP) and Epstein-Barr virus (EBV) are accepted carcinogenic and infection is widely spread in the Peruvian population. The aims of this study were to evaluate HP and EBV-associated GC (EBVaCG), to assess the prevalence rate and to define the characteristics of Peruvian patients. GC samples were prospectively collected from patients who underwent gastroscopy or surgical resection with no preoperative treatment at INEN between 2015 and 2017. Tumor tissue (T), proximal healthy tissue (P) and distal healthy tissue (D) samples were assessed for HP and EBV by quantitative PCR (qPCR) using specific primers. HP and EBV status were analyzed along with clinicopathologic parameters of the tumor. Kaplan-Meier estimation curves overall survival (OS) was appli...

BACKGROUND The influence of Helicobacter-pylori (H. pylori) infection and the characteristics of gastric cancer (GC) on tumor-infiltrating lymphocyte (TIL) levels has not been extensively studied. Analysis of infiltrating-immune-cell subtypes as well as survival is necessary to obtain comprehensive information. AIM To determine the rates of deficient mismatch-repair (dMMR), HER2-status and H. pylori infection and their association with TIL levels in GC. METHODS Samples from 503 resected GC tumors were included and TIL levels were evaluated following the international-TILs-working-group recommendations with assessment of the intratumoral (IT), stromal (ST) and invasive-border (IB) compartments. The density of CD3, CD8 and CD163 immune cells, and dMMR and HER2-status were determined by immunohistochemistry (IHC). H. pylori infection was evaluated by routine histology and quantitative PCR (...