Associations between gastric cancer risk and virus infection other than Epstein-Barr virus: The protocol of a systematic review and meta-analysis based on epidemiological studies

Prevalence Difference of Helicobacter pylori Infection Between Tibetan and Han Ethnics in China: A Meta-analysis on Epidemiologic Studies (SIGES)

China is a multi-ethnic country, and the prevalence of Helicobacter pylori ( H pylori) infection may be diverse among ethnics. This meta-analysis was conducted to compare the prevalence of H pylori infection between Tibetans and Han ethnics. Ten studies that reported the prevalence of H pylori infection between Tibetans and Hans in China were eligible. The pooled prevalence of H pylori infection was 62.2% versus 55.3% among Tibetans and Hans, respectively. Tibetans had a higher risk of H pylori infection than Hans (odds ratio [OR] = 1.38, 95% confidence interval [CI] [1.05, 1.80]). In subgroup analysis, Tibetans with upper gastrointestinal symptoms (OR = 1.51, 95% CI [1.06-2.16]), inhabiting in Tibet (OR = 1.51, 95% CI [1.22, 1.87]), or inhabiting in Northwestern region (OR = 1.15, 95% CI [1.00, 1.31]) had significantly higher risks of H pylori infection. In addition, in the recent 10 years, Hans showed a decreased risk of H pylori infection (OR = 1.81, 95% CI [1.42, 2.30]). Heterogeneity was common, while sensitivity analyses showed partially inconsistent results against main findings. This study demonstrated higher prevalence of H pylori infection in Tibetans compared with Hans, especially in recent years, or in Tibet and northwest China, as well as symptomatic Tibetans. The results suggest tailored strategy and robustness need to be further considered for H pylori screening and eradication among Tibetans.

Associations Between Gastric Cancer Risk and Virus Infection Other Than Epstein-Barr Virus: A Systematic Review and Meta-analysis Based on Epidemiological Studies

INTRODUCTION

Besides Helicobacter pylori and Epstein-Barr virus, other viruses might play potential roles in gastric carcinogenesis. This systematic review and meta-analysis was conducted to compare the prevalence of the viruses between gastric cancer (GC) and any controls.

METHODS

Comprehensive literature was searched up to January 25, 2019, and search was updated on April 6, 2020. The studies that compared the prevalence of viruses other than Epstein-Barr virus between GC and healthy or nonmalignant controls were eligible. Stata 12.0 software was used for heterogeneity tests and meta-analyses. Meanwhile, subgroup analysis, sensitivity analysis, and publication bias evaluation were performed where applicable. The power (1-β) was estimated by the PASS 11 software for each individual study.

RESULTS

A total of 41 eligible studies were included, concerning 11 kinds of viruses. Prevalence were significantly higher in GC for hepatitis B virus (odds ratio [OR] = 1.39, 95% confidence interval [CI] 1.11-1.75), human cytomegalovirus (OR = 2.25, 95% CI 1.14-4.43), human papillomavirus (HPV) (OR = 1.63, 95% CI 1.05-2.54), and John Cunningham virus (OR = 2.52, 95% CI 1.26-5.04). In subgroup analyses, HPV-16 infection was significantly associated with GC (OR = 2.42, 95% CI 1.00-5.83).

DISCUSSION

This study demonstrated that hepatitis B virus, human cytomegalovirus, HPV, and John Cunningham virus were more prevalent in GC. However, the causal relationship between their infection and risk of GC remains inconclusive, and further investigations are required.

Associations between hepatitis B virus exposure and the risk of extrahepatic digestive system cancers: A hospital-based, case-control study (SIGES)

OBJECTIVES

This case-control study was aimed to investigate associations between HBV infection and extrahepatic digestive system cancers.

METHODS

The patients of gastric, small intestinal, colonic, rectal, anal, biliary tract, and pancreatic cancers were retrospectively collected between 2016.5 and 2017.12. Simultaneously, the healthy controls were collected from the health check-up registry, and cancer-free status was confirmed based on medical records. Propensity score matching was performed to reduce bias. Multinomial logit model and conditional logistic regression model were used to assess the risk of individual cancer according to HBV serological markers and classifications.

RESULTS

Totally, 4748 patients involving seven cancers, and 57,499 controls were included. After matching, HBsAg was associated with increased risk of gastric cancer (aOR = 1.39, 95% CI: 1.05-1.85), and anti-HBs served as a protective factor for gastric (aOR = 0.72, 95% CI: 0.61-0.85), colonic (aOR = 0.73, 95% CI: 0.60-0.89), rectal (aOR = 0.73, 95% CI: 0.63-0.85), and pancreatic (aOR = 0.58, 95% CI: 0.42-0.82) cancers. Compared to subgroups with non-infection and vaccination status, inactive HBsAg carriers and active HBV infection subgroup were correlated with gastric carcinogenesis (aOR = 1.41, 95% CI: 1.03-1.93). However, no clear association was found between HBV infection and other cancers.

CONCLUSIONS

HBV infection was potentially associated with an increased risk of gastric cancer. The development mechanism of HBV-associated gastric cancer needs to investigate further.

Major Histocompatibility Complex Class I-Related Chain A (MICA) Allelic Variants Associate With Susceptibility and Prognosis of Gastric Cancer

Gastric cancer (GC) is the fifth most prevalent type of cancer worldwide. Gastric tumor cells express MICA protein, a ligand to NKG2D receptor that triggers natural killer (NK) cells effector functions for early tumor elimination. MICA gene is highly polymorphic, thus originating alleles that encode protein variants with a controversial role in cancer. The main goal of this work was to study MICA gene polymorphisms and their relationship with the susceptibility and prognosis of GC. Fifty patients with GC and 50 healthy volunteers were included in this study. MICA alleles were identified using Sanger sequencing methods. The analysis of MICA gene sequence revealed 13 MICA sequences and 5 MICA-short tandem repeats (STR) alleles in the studied cohorts We identified MICA^*002 (^*A9) as the most frequent allele in both, patients and controls, followed by MICA^*008 allele (^*A5.1). MICA^*009/049 allele was significantly associated with increased risk of GC (OR: 5.11 [95% CI: 1.39–18.74], p = 0.014). The analysis of MICA-STR alleles revealed a higher frequency of MICA^*A5 in healthy individuals than GC patients (OR = 0.34 [95% CI: 0.12–0.98], p = 0.046). Survival analysis after gastrectomy showed that patients with MICA^*002/002 or MICA^*002/004 alleles had significantly higher survival rates than those patients bearing MICA^*002/008 (p = 0.014) or MICA^*002/009 (MICA^*002/049) alleles (p = 0.040). The presence of threonine in the position MICA-181 (MICA^*009/049 allele) was more frequent in GC patients than controls (p = 0.023). Molecular analysis of MICA-181 showed that the presence of threonine provides greater mobility to the protein than arginine in the same position (MICA^*004), which could explain, at least in part, some immune evasion mechanisms developed by the tumor. In conclusion, our findings suggest that the study of MICA alleles is crucial to search for new therapeutic approaches and may be useful for the evaluation of risk and prognosis of GC and personalized therapy.

Prevalence of atrophic gastritis in southwest China and predictive strength of serum gastrin-17: A cross-sectional study (SIGES)

A hospital-based cross-sectional study in SIGES project was conducted during 2016.5–2017.5 in West China Hospital. It was aimed to observe the prevalence of atrophic gastritis (AG) in southwest China, and assess the diagnostic strength of serum gastrin-17 (G-17) in predicting AG in Chinese population. Asymptomatic healthy controls from health check-up, cancer-free patients with unspecific upper gastrointestinal symptoms, and histologically proven gastric cancer patients were eligible, if serum pepsinogen-I (PG-I), PG-II, and G-17 were detected. AG status was classified by the accredited cutoffs of PG-I (<70 ug/L) and PG-I/II ratio (<3). Totally, healthy controls (n = 9,425), symptomatic patients (n = 671) and gastric cancer patients (n = 305) were simultaneously observed, in which the prevalence of AG in southwest China were estimated as 15.9/1,000, 28.3/1,000, and 55.7/1,000 persons, respectively. The age-specific prevalence of AG in healthy controls showed a significantly uphill trend (p for trend <0.001). Higher level of serum G-17 was significantly associated with increased risk of AG in healthy population (15–30 pmol/L, aOR = 20.67, 95% CI 9.17–46.55; >30 pmol/L, aOR = 314.41, 95% CI 166.10–595.12). Throughout the progression of stomach diseases, the diagnostic strength of serum G-17 for AG showed a downhill trend across more advanced situations. In despite of that, serum G-17 displayed a good performance in predicting AG in the entire cross-sectional population (AUC = 0.92, 95% CI 0.89–0.94; SEN = 85.5%; SPE = 93.2%; LR+ = 12.55; LR− = 0.11). Population in southwest China had intermediate prevalence of AG, while the prevalence was increased over age or disease progression. High level of serum G-17 might be a reliable non-invasive measurement to predict AG in southwest Chinese population.

Helicobacter pylori prevalence in the Southwest of China: A protocol for systematic review

OBJECTIVES

This epidemiological research will be aimed to evaluate the longitudinal changes of Helicobacter pylori prevalence in Southwest China during recent period through a systematic review and analysis.

METHODS

The database PubMed and China National Knowledge Infrastructure will be searched. The cross-sectional studies or cohort studies on either massive or hospital-based health checkup population will be potentially eligible. The study population was originated from one of the southwestern major cities, Chengdu (Sichuan), Chongqing, Kunming (Yunnan), Guiyang (Guizhou), or Lhasa (Tibet). Two reviewers will independently select studies, extract data, and assess the quality of studies. The prevalence of H pylori infection will be estimated. In the individual city, the longitudinal comparisons will be conducted to evaluate the trends referring to the earliest cross-sectional baseline. The risk ratio and its 95% confidence interval will be estimated. Subgroup analyses will be performed in sex-specific and age-specific subsets. Trend analysis for proportions (p for trend) will be estimated in the longitudinal evaluation. If applicable, the longitudinal clearance rate (%) will be estimated.

ETHICS AND DISSEMINATION

The ethical approval is not required due to the nature of literature-based research. The results will be disseminated through meetings and a peer-reviewed journal.

PROSPERO REGISTRATION NUMBER

CRD42019120764.