Comprehensive analysis of proton pump inhibitors and risk of digestive tract cancers

Proton pump inhibitors and the risk of gastric cancer: a systematic review, evidence synthesis and life course epidemiology perspective

OBJECTIVES

Since proton pump inhibitors (PPI) have been introduced, many concerns were raised regarding potential gastric carcinogenicity. We aim to summarise and weigh the epidemiological evidence and address possible causality.

DESIGN

Systematic literature review, evidence synthesis and life-course assessment.

DATA SOURCES

PubMed, Web of Science and Cochrane database (from inception up to October 2024), and back- and forward citation tracking (Web of Science).

ELIGIBILITY CRITERIA

Original studies and quantitative evidence syntheses assessing the association between PPIs and gastric cancer in humans, without language restrictions.

DATA EXTRACTION AND SYNTHESIS

Study design, definitions (and participant numbers) of PPI use and gastric cancer, study characteristics (setting, period, follow-up, lag-time), age and sex distribution presented in tables and evidence mapping.

RESULTS

We identified 33 original studies, 21 meta-analyses, three umbrella meta-analyses, one individual patient data meta-analysis and a Markov model (2006-2023). PPIs were consistently associated with an increased gastric cancer risk with 20/21 meta-analyses reporting pooled relative risks between 1.3 and 2.9. Available trials were underpowered. Reverse causation/protopathic bias, residual confounding (by indication) and lag time seem the largest methodological challenges, as well as disentangling the effects of Helicobacter pylori and its' eradication. Insufficient data are available on age and sex-specific risks, with no studies specifically addressing PPIs in young populations. We hypothesise a sensitive-period exposure model, in which PPI use during pregnancy and early life may be particularly damaging regarding long-term cancer risk. An exploration of Swedish cancer incidence data suggests potential cohort effects as overall gastric cancer risk decreased over time (1970-2022). The risk has increased in young (<40 years) men since the early 2000s, ~10 years after the introduction of Helicobacter pylori eradication and PPIs.

CONCLUSION

Although for older individuals with valid indications, the gastric cancer risk related to PPI use may be limited, we do argue for a more rational and evidence-supported use of PPIs in young populations.

Prenatal and Early Childhood Exposure to Proton Pump Inhibitors and Antibiotics and the Risk of Childhood Cancer: A Nationwide Population-Based Cohort Study

BACKGROUND

Our microbiome is established during infancy, a time important for later health and long-term effects. Proton pump inhibitors and antibiotics are regularly prescribed during pregnancy. Both drugs cause microbiome disturbance and have been associated with increased cancer risk in adults, but effects of these drugs on the growing foetus and infant remain understudied.

AIM

The aim of this study is to study the association between prenatal and early life proton pump inhibitor and antibiotics exposure and the risk of childhood cancer.

METHODS

This study is a retrospective population-based cohort design, using registry data on all births (n = 722,372) in Sweden between 2006 and 2016, according to the STROBE checklist. For women who had multiple children in the timeframe of the study, only the first child during the time period was included in the cohort. Exposure was defined as either ≥ 1 proton pump inhibitor or antibiotics prescription during pregnancy, or during the first 2 years of life. Outcome was defined as cancer at any time during the follow-up or cancer after the age of 2 years for early life exposure. Multivariable Cox proportional hazard models were used to calculate hazard ratios.

RESULTS

In total, 1091 (0.2%) children were diagnosed with malignant cancer during the follow-up. Prenatal exposure to proton pump inhibitors and antibiotics were not associated with an increased risk of cancer. Regarding early life exposure, proton pump inhibitors were associated with an increased risk of cancer at age two or older (adjusted hazard ratio [aHR] 3.68, 95% confidence interval [CI] 2.24-6.06).

CONCLUSIONS

We did not find evidence that prenatal proton pump inhibitors and antibiotics were associated with overall childhood cancer. However, proton pump inhibitors during early life were associated with an increased risk of childhood cancer, but indication on drug use was not available and confounding by indication may be present.

Risk of Esophageal Adenocarcinoma After Helicobacter pylori Eradication Treatment in a Population-Based Multinational Cohort Study

BACKGROUND & AIMS

Helicobacter pylori infection is associated with a decreased risk of esophageal adenocarcinoma, and the decreasing prevalence of such infection might contribute to the increasing incidence of this tumor. We examined the hypothesis that eradication treatment of H pylori increases the risk of esophageal adenocarcinoma.

METHODS

This population-based multinational cohort, entitled "Nordic Helicobacter Pylori Eradication Project (NordHePEP)," included all adults (≥18 years) receiving H pylori eradication treatment from 1995-2018 in any of the 5 Nordic countries (Denmark, Finland, Iceland, Norway, and Sweden) with follow-up throughout 2019. Data came from national registers. We calculated standardized incidence ratios (SIRs) with 95% confidence intervals (CIs) by dividing the cancer incidence in the exposed cohort by that of the entire Nordic background populations of the corresponding age, sex, calendar period, and country. Analyses were stratified by factors associated with esophageal adenocarcinoma (ie, education, comorbidity, gastroesophageal reflux, and certain medications).

RESULTS

Among 661,987 participants who contributed 5,495,552 person-years after eradication treatment (median follow-up, 7.8 years; range, 1-24 years), 550 cases of esophageal adenocarcinoma developed. The overall SIR of esophageal adenocarcinoma was not increased (SIR = 0.89; 95% CI, 0.82-0.97). The SIR did not increase over time after eradication treatment, but rather decreased and was 0.73 (95% CI, 0.61-0.86) at 11-24 years after treatment. There were no major differences in the stratified analyses. The overall SIR of esophageal squamous cell carcinoma, calculated for comparison, showed no association (SIR = 0.99; 95% CI, 0.89-1.11).

CONCLUSIONS

This absence on an increased risk of esophageal adenocarcinoma after eradication treatment of H pylori suggests eradication is safe from a cancer perspective.

Does proton pump inhibitors use increase risk of digestive tumors?: A 2-sample Mendelian randomization study

The objective of this study was to explore the causal relationship between the use of proton pump inhibitors (PPIs) and 16 types of digestive system tumors. We utilized a 2-sample Mendelian randomization (MR) approach to investigate this relationship. We obtained exposure and outcome data from the UK Biobank and the Finland Biobank, respectively. The genetic data used in the analysis were derived from genome-wide association studies (GWAS) studies conducted on European populations. We screened single nucleotide polymorphisms significantly associated with the use of omeprazole, a commonly used PPIs, as instrumental variables. We then performed MR analyses using the inverse variance weighting (IVW) method, MR-Egger regression, and the weighted median method to evaluate the causal effect of omeprazole use on the 16 types of digestive system tumors. Our MR analysis revealed a significant causal relationship between the use of omeprazole and pancreatic malignancies, but not with any other types of digestive system tumors. The IVW analysis showed an odds ratio of 4.33E-05 (95%CI: [4.87E-09, 0.38], P = .03) and the MR-Egger analysis showed an odds ratio of 5.81E-11 (95%CI: [2.82E-20, 0.12], P = .04). We found no significant heterogeneity or pleiotropy, and sensitivity analysis confirmed the robustness of our results. Furthermore, statistical power calculations suggested that our findings were reliable. Conclusion The use of PPIs is a protective factor for pancreatic malignancies, but no causal relationship has been found with other digestive system tumors.

Intake of Proton-Pump Inhibitors and Gastric Cancer within the Stomach Cancer Pooling (StoP) Project

BACKGROUND

A potential association between proton-pump inhibitors (PPI) and gastric cancer remains undefined. Thus, we aimed to evaluate such association within the Stomach cancer Pooling (StoP) Project.

METHODS

Data from five case-control studies of the StoP Project were included (1,889 cases and 6,517 controls). We assessed the impact of different exposure definitions, specifically any reported use of PPIs and exposure definitions based on the duration of PPI intake. Additionally, we modeled the dose-response relationship between the cumulative duration of PPI intake and gastric cancer.

RESULTS

Significant associations between PPI intake and gastric cancer, both overall and in the stratified analyses, were limited to exposure definitions based on short durations of intake. The overall odds ratio (OR) for any reported PPI intake was 1.78 [95% confidence interval (CI): 0.76-4.14]. In the dose-response analysis, the ORs of gastric cancer were found to be higher for short durations of PPI intake (6 months: OR 3.26; 95% CI: 2.40-4.42; one year: OR 2.14; 95% CI: 1.69-2.70; 2 years: OR 1.50; 95% CI: 1.22-1.85; 3 years: OR 1.27; 95% CI: 1.03-1.56), with the association becoming not significant for durations longer than 3 years.

CONCLUSIONS

Our findings suggest that the observed association between PPIs and gastric cancer might be mainly due to reverse causality.

IMPACT

The results of this study suggest that PPIs are a safe therapeutic choice regarding their effect on the occurrence of gastric cancer. See related commentary by Richman and Leiman, p. 1127.

Can We StoP Worrying about Long-term PPIs and Gastric Cancer Risk?

Proton pump inhibitors (PPI) are a cornerstone of management for many digestive diseases. While chronic PPI use induces physiologic changes including gastric acid suppression and hypergastrinemia, existing data are conflicting on whether this impacts the risk of gastric cancer among PPI users. Sassano and colleagues utilized pooled case-control data from five studies in the Stomach cancer Pooling (StoP) Project to investigate the association between PPI use and histologically confirmed gastric cancer. Short-term PPI use (6 months) was associated with increased risk of gastric cancer, but no association was found between long-term PPI use (3 years or more) and gastric cancer. Although the authors relied on patient-reported PPI use data, and data related to Helicobacter pylori infection and eradication rates were missing, no histologic gastric cancer subtypes in this international case-control study were associated with any PPI use. Currently reported findings provide patients and clinicians with reassuring observations that long-term PPI use does not significantly increase gastric cancer risk. The relationship identified among short-term PPI users may reflect reverse causality. Our understanding will be furthered by additional assessment of potential confounders, including comorbid conditions, PPI metabolism, and social determinants of health. See related article by Sassano et al., p. 1174.

The Protease Inhibitor Amprenavir Protects against Pepsin-Induced Esophageal Epithelial Barrier Disruption and Cancer-Associated Changes

Gastroesophageal reflux disease (GERD) significantly impacts patient quality of life and is a major risk factor for the development of Barrett's esophagus (BE) and esophageal adenocarcinoma (EAC). Proton pump inhibitors (PPIs) are the standard-of-care for GERD and are among the most prescribed drugs in the world, but do not protect against nonacid components of reflux such as pepsin, or prevent reflux-associated carcinogenesis. We recently identified an HIV protease inhibitor amprenavir that inhibits pepsin and demonstrated the antireflux therapeutic potential of its prodrug fosamprenavir in a mouse model of laryngopharyngeal reflux. In this study, we assessed the capacity of amprenavir to protect against esophageal epithelial barrier disruption in vitro and related molecular events, E-cadherin cleavage, and matrix metalloproteinase induction, which are associated with GERD severity and esophageal cancer. Herein, weakly acidified pepsin (though not acid alone) caused cell dissociation accompanied by regulated intramembrane proteolysis of E-cadherin. Soluble E-cadherin responsive matrix metalloproteinases (MMPs) were transcriptionally upregulated 24 h post-treatment. Amprenavir, at serum concentrations achievable given the manufacturer-recommended dose of fosamprenavir, protected against pepsin-induced cell dissociation, E-cadherin cleavage, and MMP induction. These results support a potential therapeutic role for amprenavir in GERD recalcitrant to PPI therapy and for preventing GERD-associated neoplastic changes.

Association of proton pump inhibitors with gastric and colorectal cancer risk: A systematic review and meta-analysis

Background: Proton pump inhibitors (PPI) are generally considered to be one of the well-established prescription drug classes and are commonly used to treat most acid-related diseases. However, a growing body of literature showing an association between gastric and colorectal cancer risk and PPI use continues to raise concerns about the safety of PPI use. Therefore, we aimed to investigate the association between proton pump inhibitor use and risk of gastric and colorectal cancer.

Methods: We collected relevant articles using PubMed, Embase, Web of Science and Cochrane library from 1 January 1990 to 21 March 2022. The pooled effect sizes were calculated based on the random-effects model. The study was registered with PROSPERO (CRD42022351332).

Results: A total of 24 studies (n = 8,066,349) were included in the final analysis in the screening articles. Compared with non-PPI users, PPI users had a significantly higher risk of gastric cancer (RR = 1.82, 95% CI: 1.46–2.29), but not colorectal cancer (RR = 1.22, 95% CI: 0.95–1.55). Subgroup analysis showed that there was a significant positive correlation between the use of PPI and the risk of non-cardiac cancer (RR = 2.75, 95% CI: 2.09–3.62). There was a significant trend between the duration dependent effect of PPI use and the risk of gastric cancer (&lt;1 year RR = 1.56, 95% CI: 1.30–1.86; 1–3 years RR = 1.75, 95% CI: 1.28–2.37; &gt;3 years RR = 2.32, 95% CI: 1.15–4.66), but not colorectal cancer (≤1 year RR = 1.00, 95% CI: 0.78–1.28; &gt;1 year RR = 1.18, 95% CI: 0.91–1.54; ≥5 years RR = 1.06, 95% CI: 0.95–1.17).

Conclusion: We found that PPI use increased gastric cancer risk, but not colorectal cancer risk. This result may be biased due to confounding factors. More prospective studies are needed to further validate and support our findings.

Systematic Review Registration: [https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022351332], identifier [CRD42022351332].

Meta-analysis: Use of proton pump inhibitors and risk of gastric cancer in patients requiring gastric acid suppression

BACKGROUND

Proton-pump inhibitors (PPIs) are suspected to increase the risk of gastric cancer.

AIM

To assess the risk of gastric cancer associated with the use of PPIs.

METHODS

We systematically searched Medline/PubMed, Embase and Scopus databases (until June 1, 2022) for randomised and non-randomised studies (NRS) of the association between PPIs and gastric cancer having considered Histamine-2 receptor antagonists (H2RAs) users as controls. We chose this comparison to minimise confounding by indication, and focus on patients requiring gastric acid suppression. Two authors independently extracted study data and assessed each study's risk of bias. Maximally-adjusted relative risk (RR) estimates were extracted. Heterogeneity and small-study effect were examined, and summary estimates were calculated using random- and fixed-effect models. Stratified analyses and meta-regression were employed to explore heterogeneity. We used GRADE to evaluate the certainty of evidence.

RESULTS

Of 8375 records, 12 NRS (>6 million patients; 11,554 gastric cancers) and two randomised clinical trials (498 patients; 1 gastric cancer) fulfilled the eligibility criteria. Randomised evidence was very imprecise and provided very-low certainty evidence. Meta-analysis of six NRS providing a comprehensive adjustment for confounding (2.5 million patients; 7372 gastric cancers) did not show any association between PPIs and gastric cancer (RR_random  = 1.07, 0.97-1.19; RR_fixed  = 1.05, 0.98-1.12). The certainty of the evidence was low. No convincing evidence of dose-response, or increased risk with long-term use, was found. Lack of or minimal adjustment for confounding was associated with larger effect sizes.

CONCLUSIONS

We found no association between PPIs and gastric cancer in NRS having adequately controlled for confounding. Published studies may suffer residual confounding.

SYSTEMATIC REVIEW REGISTRATION

CRD42022335971.

Exposure to Commonly Used Drugs and the Risk of Gastric Cancer: An Umbrella Review of Meta-Analyses

Recently, attention has been paid to some medications and gastric cancer (GC) risk. This review aimed to evaluate associations between commonly used drugs and GC risk and to grade evidence from published systematic reviews and meta-analyses. This umbrella review was registered in PROSPERO (CRD42022320276). The systematic reviews and meta-analyses of observational studies were retrieved by searching Embase, PubMed, and Web of Science. The evidence strength of commonly used drugs and GC risk was categorized into four grades: weak, suggestive, highly suggestive, and strong. Of 19 associations between commonly used drugs and GC risk and its subtypes, none was supported by convincing or highly suggestive evidence. The risk of GC related to non-steroidal anti-inflammatory drugs (NSAIDs), non-aspirin NSAIDs, and acid-suppressive drugs, as well as the risk of non-cardia GC related to NSAIDs and aspirin, was supported by suggestive evidence. The results showed that a reduced GC risk was associated with two drug types (NSAIDs and non-aspirin NSAIDs), and an increased GC risk was associated with acid-suppressing drugs at the suggestive evidence level. Moreover, NSAIDs and aspirin reduced non-cardia GC risk as supported by suggestive evidence. However, the evidence supporting statins or metformin in reducing GC risk was weak, and thus future studies are required to clarify these associations.

Proton Pump Inhibitor Use and Obesity-Associated Cancer in the Women's Health Initiative

Proton pump inhibitors (PPIs) have off-target activity on fatty acid synthase (FASN), a critical enzyme in energy balance and cancer growth. We evaluated risk of common obesity-related cancers: breast, colorectal (CRC), and endometrial, with use of PPI and histamine-2 receptor antagonists (H2RA) in 124,931 postmenopausal women enrolled in the Women's Health Initiative. Incident cancer cases were physician-adjudicated. Cox proportional hazards models were used to estimate multivariable hazard ratios (HR) and 95% confidence intervals (CI) for cancer incidence after year 3. There were 7956 PPI ever users and 9398 H2RA only users. Ever use of either PPI or H2RA was not associated with risk of breast cancer (n = 9186) nor risk of endometrial cancer (n = 1231). The risk of CRC (n = 2280) was significantly lower in PPI users (HR = 0.75, 95% CI = 0.61-0.92), but not in H2RA users (HR = 1.13, 95% CI = 0.97-1.31). The association of PPI use with CRC was apparent regardless of BMI or NSAID use, and was stronger with longer PPI duration (p = 0.006) and potency (p = 0.005). The findings that PPI use, but not H2RA use, demonstrate an inverse dose-response relationship with risk of CRC is consistent with preclinical data showing FASN inhibition prevents colon cancer progression and supports a role of PPI in CRC prevention.