Background Helicobacter pylori is an important carcinogenic factor in gastric cancer. Studies have shown that Helicobacter pylori infection is inversely associated with certain diseases such as esophageal cancer and whose infection appears to have a “protective effect.” At present, the relationship between Helicobacter pylori infection and esophageal cancer remains controversial. This study was designed to investigate the relationship between Helicobacter pylori infection and the risk of esophageal cancer in different regions and ethnicities. Methods Systematic search of the articles on the relationship between Helicobacter pylori infection and esophageal cancer from the database with the duration time up to December 2018. This systematic review was performed under the MOOSE guidelines. Results This meta-analysis included 35 studies with 345,886 patients enrolled. There was no significant correlation between Helicobacter pylori infection and esophageal squamous cell carcinoma in the general population (OR: 0.84; 95% CI: 0.64-1.09/OR: 0.74; 95% CI: 0.54-0.97). However, a significant correlation was found in the Middle East (OR: 0.34; 95% CI: 0.22-0.52/95% CI: 0.26-0.44). There was no significant difference in the prevalence of Helicobacter pylori between the case group and the control group in esophageal adenocarcinoma (8.87% vs. 9.67%). The pooled OR was 0.55 (95% CI: 0.43-0.70) or 0.23 (95% CI: 0.15-0.36). When grouped by match or not, the pooled OR of the nonmatching group and the matching group was 0.48/0.21 (95% CI: 0.36-0.65/95% CI: 0.13-0.36) and 0.73/0.71 (95% CI: 0.57-0.92/95% CI: 0.60-0.84), respectively. Conclusion In the general populations, no significant association was found between Helicobacter pylori infection and the risk of esophageal squamous cell carcinoma. However, lower risk was found in the Middle East. Helicobacter pylori infection may reduce the risk of esophageal adenocarcinoma, but such “protection effect” may be overestimated.

Aims: To profile and characterize the circular RNA (circRNA) expression pattern in poorly differentiated gastric adenocarcinoma (PDGA). Methods & materials: CircRNA expression profiles in PDGA and adjacent nontumor tissues were analyzed by microarray. Five randomly selected differentiated expressed circRNAs (DECs) were validated by real-time quantitative PCR. m6A qualification of the top 20 DECs was conducted by m6A-immunoprecipitation and real-time quantitative PCR. Results: A total of 65 DECs were found in PDGA compared with the control. Hsa_circRNA_0077837 had the largest area under the curve. Most DECs had m6A modifications, the trend of m6A modification alteration was mainly consistent with the circRNA expression level. Conclusion: Our study revealed a set of DECs and their m6A modification alterations, which may provide new insight for their potential function in PDGA.

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