Journal of Cancer Research and Therapeutics

ORIGINAL ARTICLE
Year
: 2016  |  Volume : 12  |  Issue : 8  |  Page : 229--232

Helicobacter pylori infection and pancreatic cancer risk: A meta-analysis


Yu Guo, Wei Liu, Jun Wu 
 Department of Clinical Laboratory, Beijing Jishuitan Hospital, Beijing, P.R. China

Correspondence Address:
Jun Wu
Department of Clinical Laboratory, Beijing Jishuitan Hospital, Beijing
P.R. China

Abstract

Objective: To assess whether the Helicobacter pylori (HP) infection can increase the risk of developing pancreatic cancer or not by meta-analysis. Methods: Published studies about HP infection and pancreatic cancer risk were electronic searched in the databases of MEDLINE, PubMed, Web of Science, and CNKI. The correlation between HP infection and pancreatic cancer was demonstrated by odds ratio (OR) and corresponding 95% confidence interval (CI). The publication bias was assessed by Begg's funnel plot and Egger's linear regression test. Results: We finally included eight case–control studies for this present meta-analysis with 1003 pancreatic cancer patients and 1754 healthy controls. One study performed in Austria, 3 from China, and 4 from the United States. For obvious statistical heterogeneity, the data were pooled by random effects model. The pooled data indicated that significant correlation between HP infection and pancreatic cancer was found with OR = 1.45 (95% CI = 1.09–1.92) under the random effects model. The results indicated that the HP infection can significantly increase the risk of developing pancreatic cancer. The publication bias was evaluated by Begg's funnel plot and Egger's linear regression test. The Begg's funnel plot was significant asymmetric at the bottom which indicated potential publication bias. The Egger's linear regression test also indicated significant publication bias (t = 3.21, P < 0.05). Conclusion: Based on present open published data, HP infection can significantly increase the risk of developing pancreatic cancer. However, for small number of studies included in this meta-analysis and publication bias, more case–control or cohort studies are needed to further confirm this conclusion.



How to cite this article:
Guo Y, Liu W, Wu J. Helicobacter pylori infection and pancreatic cancer risk: A meta-analysis.J Can Res Ther 2016;12:229-232


How to cite this URL:
Guo Y, Liu W, Wu J. Helicobacter pylori infection and pancreatic cancer risk: A meta-analysis. J Can Res Ther [serial online] 2016 [cited 2017 Mar 25 ];12:229-232
Available from: http://www.cancerjournal.net/text.asp?2016/12/8/229/200744


Full Text

 Introduction



Pancreatic cancer is one of the most diagnosed solid malignant carcinomas with poor prognosis.[1],[2] It was reported that pancreatic cancer was more likely to happen in developed countries than developing countries.[3] However in the recent years, with lifestyle and eating habits changing, the incidence of pancreatic cancer in developing countries is on the rise. The reason for pancreatic cancer was not absolutely clear, but the epidemiologic study showed that smoking,[4] genetics,[5] high-fat diet,[6] chronic pancreatitis, gallstone disease, peptic ulcer, and cholecystectomy can increase the incidence of pancreatic cancer. Moreover, several epidemiological publications also showed that patients with Helicobacter pylori (HP) infection prone to have pancreatic cancer.[7] Because of the small number of cases and different study designs for the individual study, the results were limited and there was lack of power. Thereby, we use open published data to do this meta-analysis to further evaluate the correlation between HP infection and pancreatic cancer risk.

 Methods



Study searching

The study searching was done by one of the reviewers through the databases of MEDLINE, PubMed, Web of Science, and CNKI. All the case–control or cohort studies related to HP infection and pancreatic cancer association were screened. The searching procedure was done according to the Cochrane library handbook. The searching words were as follows: “Helicobacter pylori,” “pancreatic cancer,” and “pancreatic neoplasm.” All the related publications for HP infection and pancreatic cancer risk were selected and screened. Furthermore, for obtaining additional relevant articles, we reviewed the conference summaries and reference lists of retrieved studies and even contacted authors to obtain further information, if necessary.

Study inclusion and exclusion

After searching the databases, the potential useful publications should be included in this study. The inclusion criteria were as follows: (1) the publication type is case–control or cohort studies; (2) the published language is English or Chinese; (3) the patients in case group should be confirmed by pathology, cytology, or computed tomography scan; (4) the data of each included study should contain enough information to calculate the odds ratio (OR). Exclusion criteria: (1) other study type such as case report or review; (2) publications other than English or Chinese; (3) duplicated published studies or data; (4) without enough data to calculate the OR.

Data extraction

Two authors extracted the data from the included publications independently. The extracted data or information include (1) the first and corresponding author's name; (2) when the paper published; (3) where the work was done; (4) the total number of cases in each group and number of HP +/HP– patients in the case and control groups. If disagreement was found in the procedure of data extraction, discussion or consulting for another reviewer was carried out.

Statistical methods

The data were analyzed by STATA/SE 11.0 software (StataCorp LP, http://www.stata.com). The pooled ORs and its 95% confidence intervals (CIs) were calculated using either the Mantel-Haenszel model (fixed-effect model) or the Dersimonian-Laird model (random-effect model). For quantitative analysis, OR and its 95% CIs were used to evaluate the association between HP infection and pancreatic risk.[8] The Begg's funnel plot and Egger's test were used to evaluate the possible publication bias.

 Results



Main information for the included studies

After searching the databases, we finally included eight case–control studies [9],[10],[11],[12],[13],[14],[15],[16] for this present meta-analysis. One study performed in Austria, 3 from China, and 4 from the United States. One thousand and three pancreatic cancer patients and 1754 healthy controls were included in this study. The HP positive rate was 57.7% ±18.8% and 47.9% ±16.5% for pancreatic cancer and healthy controls, respectively, with statistical difference (P < 0.05). The general information for the included publications is shown in [Table 1].{Table 1}

Heterogeneity across the included studies

The heterogeneity across the included eight studies was evaluated by I2 test. Moreover, significant statistical heterogeneity was existed across the studies with the I2 = 54.4% (P < 0.05). The combined OR was pooled by random effects model.

Association between Helicobacter pylori infection and pancreatic cancer risk

For obvious statistical heterogeneity, the data were pooled by random effects model. The pooled data indicated that significant correlation between HP infection and pancreatic cancer was found with OR = 1.45 (95% CI = 1.09–1.92) under the random effects model [Figure 1]. The results indicated that the HP infection can significantly increase the risks of developing pancreatic cancer.{Figure 1}

Publication bias

The publication bias was evaluated by Begg's funnel plot and Egger's linear regression test. The Begg's funnel plot was significant asymmetric at the bottom which indicated potential publication bias. The Egger's linear regression test also indicated significant publication bias (t = 3.21, P < 0.05) [Figure 2].{Figure 2}

 Discussion



Pancreatic cancer is the 5th leading cause of cancer-related death worldwide.[1] Moreover, it rarely occurs before the age of 40 years, and more than half of cases of pancreatic carcinoma occur in those over 70 years old. According to the previous study, risk factors for pancreatic cancer include tobacco smoking, obesity, diabetes, and certain genetic conditions.[17] About 25% of cases are linked to smoking and 5%–10% are linked to inherited genes.[18] Recent studies also found that people with HP(+) infection may increase the risk of developing pancreatic cancer. Li et al. reported a case–control study to evaluate the correlation between HP infection and pancreatic risk. In their study, the author included 56 cases with diagnosed pancreatic cancer and 60 healthy controls. They found that the HP infection rate was 64.29% and 46.27% for pancreatic cancer patients and healthy controls, respectively, with statistical difference (P < 0.05). These results indicated that the HP can increase the pancreatic risk. However, another study carried out by de Martel et al. found that the HP infection was not associated with the development of pancreatic cancer. After searching the databases, we found that several publications have discussed the relationship between HP infection and pancreatic risk. However, the results of each study were not in accordance with each other for a small number of cases included in each individual study, different study design, and different cases and controls.

To further evaluate the association between HP infection and pancreatic risk, we perform this present meta-analysis. We included 8 case–control studies with 1003 pancreatic cancer patients and 1754 healthy controls. The pooled data indicated that significant correlation between HP infection and pancreatic cancer was found with OR = 1.45 (95% CI = 1.09–1.92) under the random effects model. The results indicated that the HP infection can significantly increase the risk of developing pancreatic cancer.

However, in this meta-analysis, two major drawbacks were existed. One is the statistical heterogeneity and the other is significant publication bias. Hence, the conclusion of this meta-analysis was limited and need to be further confirmed by more high-quality case–control or cohort studies.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

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