BACKGROUND: 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. METHODS: 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 applied. Comparison between qPCR detection and current standard methods of detection was also performed. All tests were two sided, and a p≤0.05 was considered statistically significant. RESULTS: A total of 150 patients were studied with a mean age 65 years and predominance of males (51.3%). Intestinal-mixed histological subtype rate was 72.5% in cases. Most frequent clinical stage was III-IV (74.6%). HP+ patients were determinate with at least one ureA/hspA gene result and EBV+ patients were divided in high viral load (>100copy/μl) and low viral load (<100copy/μl) groups. Results found HP in 87.3% (n=131/150) and EBV in 10% (n=15/150) of the population. Cases and HP concentration were higher in D (ureA: 62.8%, [703.58±245.47pg]; hspA: 73.8%, [42.77±10.17pg]) than P (ureA: 59.0%, [539.69±121.32pg]; hspA: 71.0%, [31.90±8.64pg]) and T (ureA: 49.7%, [296.32±164.98pg]; hspA: 70.5%, [4.6±1.33pg]) (p<.001). High viral load EBV was found in 40% (n=6/15) of cases. Co-infection detection rate was 7.3% (n=11/150). Correlation between qPCR and H&E evaluation of HP was found in only 72.9% (n=19/57) of cases without evidence of HP (p<.001) and no detectable expression of EBV was found by EBER in qPCR positive cases (n= 15). Cases were defined in 4 groups: HP+EBV+ (n=9), HP+EBV- (n=98), HP-EBV+ (n=6), and HP-EBV- (n=37). Results showed median age (67, 66, 67 and 66), most frequent III-IV clinical stage (75%, 69.5%, 72.7% and 62.1%), histologic grade found was GII (50%, 28.8%, 50% and 43.3%) and intestinal-mixed histological subtype (66.6%, 56.6%, 100% and 62.1%) in four groups respectively. EBVaGC was associated to OS (38.3% vs 72.3%) at 1 year, p=0.033). Based on a mean follow-up of 24 months, the 1-year survival was lower in EBV+ [45.5% (HP+ EBV+) and 25% (HP- EBV+)] than in EBV- [73.1% (HP+ EBV-) and 61.5% (HP- EBV-)] groups. CONCLUSION: HP infection is frequent in Peruvian CG patients. Presence of HP and EBV infection evaluated by qPCR define 4 groups with different features and survival. Study supported by CIENCIACTIVA-CONCYTEC, under the contract #196-2015-FONDECYT.

Citation Format: Carolina Belmar López, Miluska Castillo Garcia, Carlos A. Castañeda Altamirano, Luis F. Barreda Bolaños, Daniel Valdivia Leonardo, Eduardo Payet Meza, Valeria Villegas Bernaola, Jais Nieves Prado, Joselyn R. Sanchez Sifuentes, Luis A. Bernabé Monsalve, Manuel A. Chumpitaz La Rosa Sanchez, Omar Mejía Dionisio, Ivan Chavez Passiuri. HP and EBVaGC in Peruvian patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4210.