Effect of glucagon-like peptide-1 receptor agonists and dipeptidyl peptidase-4 inhibitors on colorectal cancer incidence and its precursors

Real-world evidence on the association of novel antidiabetic medication use with cancer risk and protective effects: a systematic review and network meta-analysis

Background

Novel antidiabetic medications (SGLT-2 inhibitors, DPP-4 inhibitors, and GLP-1 agonists) are commonly used worldwide; however, the available research lacks definitive conclusions on their protective effects or potential risks on cancer.

Objectives

Compared to other antidiabetics, our systematic review and network meta-analysis (NMA) aims to use real-world studies to assess the potential cancer risks or protective effects of these novel antidiabetics.

Methods

We comprehensively searched PubMed, CINAHL, and Web of Science from their inception until November 30, 2023. We included observational studies examining at least one novel antidiabetics in the systematic review. The novel antidiabetics include sodium-glucose cotransporter-2 inhibitors (SGLT-2i), dipeptidyl peptidase-4 inhibitors (DPP-4i), and glucagon-like peptide-1 agonists (GLP-1a).

Design

We focused on cohort studies that provided data on cancer incidence and sample size in the NMA. Using NetMetaXL®, the random effects model with informative priors was used in the NMA to estimate the pooled odds ratio (OR) with 95% credible intervals (CrI).

Results

The systematic review included 62 studies, of which 22 met the inclusion criteria for the NMA. SGLT-2i users had lower overall cancer risk compared to sulfonylureas (OR: 0.54; 95% CrI: 0.40-0.74, low certainty), GLP-1a (OR: 0.70; 95% CrI: 0.53-0.92, low certainty), and DPP-4i users (OR: 0.72; 95% CrI: 0.57-0.92, very low certainty). DPP-4i users also had a lower cancer risk than sulfonylureas users (OR: 0.76; 95% CrI: 0.60-0.96, low certainty). No other statistically significant ORs were found in other direct comparisons.

Conclusion

SGLT-2i users have a lower risk of developing cancers than sulfonylureas, GLP-1a, and DPP-4i users. These results may improve patient safety by guiding future clinical practice and medication choices. Future studies should investigate the mechanisms behind these observed associations.

Trial registration

This NMA was registered in PROSPERO (CRD42023469941).

Impact of dipeptidyl peptidase-4 inhibitors on incidence of colorectal cancer in patients with type 2 diabetes mellitus: a systematic review and meta-analysis

Background

The association between dipeptidyl peptidase-4 inhibitors (DPP-4i) exposure and the risk of colorectal cancer (CRC) in patients with type 2 diabetes mellitus (T2DM) is unclear.

Objectives

This meta-analysis aims to investigate the relationship between DPP-4i exposure and the incidence of CRC in patients with T2DM.

Design

A systematic review and meta-analysis.

Methods

A comprehensive search of electronic databases, including PubMed, Web of Science, EMBASE, and ScienceDirect, was conducted up to March 2024. The studies including randomized clinical trials (RCTs), cohort studies, and case-control studies were retrieved. The odds ratio (OR) was calculated using Stata 12.0 statistical software. The primary outcome assessed was the incidence of CRC.

Results

This meta-analysis incorporated six retrospective cohort studies and two case-control studies. The findings indicate that the incidence of CRC in the DPP-4i exposure group was significantly higher than that in the control group (OR = 1.11, 95% CI: 1.02-1.21, p = 0.013). Subgroup analysis revealed that both male (OR = 2.07, p < 0.001) and female participants (OR = 1.49, p = 0.05) in the DPP-4i exposure group exhibited a significantly higher incidence of CRC compared to the control group. Among participants younger than 65 years, the incidence of CRC was markedly elevated in the exposure group (OR = 2.81, p < 0.001). Furthermore, when the exposure duration was less than 1 year, the CRC incidence in the exposure group surpassed that of the control group (OR = 1.24, p = 0.005). When sulfonylureas (SU) were used as control drugs, the incidence of CRC was higher in the exposure group (OR = 1.10, p = 0.017).

Conclusion

There is a potential correlation between DPP-4i exposure and increased incidence of CRC in T2DM patients. This association appears to be influenced by gender, age, duration of exposure, and the choice of control medications. Therefore, attention should be paid to colorectal diseases when DPP-4i is employed in the clinic.

Trial registration

The meta-analysis has been registered with the International Prospective Register of Systematic Reviews (PROSPERO). The registration number is CRD42024535292.

Association Between GLP1 RAs Use and Risk of Colorectal Cancer: A Systematic Review and Meta-Analysis

Background and Objective

As the global prevalence of type 2 diabetes mellitus (T2DM) continues to rise, addressing its associated health risks, including colorectal cancer (CRC), is important. This study examines the relationship between the use of glucagon-like peptide-1 receptor agonists (GLP-1RAs) and the risk of CRC in comparison with other antidiabetic therapies.

Methods

We conducted a systematic search of PubMed, Embase, and Web of Science up to August 10, 2024, following PRISMA guidelines. Data extraction and screening were performed using Nested Knowledge software. Meta-analysis random effect model pooled Risk ratios (RRs) calculated using was performed using R v4.4 statistical software g. The protocol was registered with PROSPERO.

Results

Out of 1825 identified studies, five met the inclusion criteria, involving 2,047,256 T2DM patients assessing CRC risk. GLP-1RAs were associated with a significant reduction in CRC risk compared to thiazolidinediones (RR: 0.82, 95% CI: 0.68-0.96), insulin (RR: 0.57, 95% CI: 0.32-0.81), and SGLT2 inhibitors (RR: 0.77, 95% CI: 0.59-0.95). Comparisons with sulfonylureas, DPP-4 inhibitors, and metformin were not statistically significant. A potential protective effect against alpha-glucosidase inhibitors was observed (RR: 0.59, 95% CI: 0.18-1.00) but requires further investigation.

Conclusion

The use of GLP-1RAs in T2DM is linked to a reduced risk of CRC compared to several standard antidiabetic therapies. These findings underscore the importance of considering long-term cancer risks in diabetes management and highlight the need for continued research to fully understand the implications of GLP-1RA use in T2DM patients.

Advancements in Understanding and Preventing Obesity-Related Colon Cancer

ABSTRACT

Obesity and colorectal cancer are global public health issues, with the prevalence of both conditions increasing over the last 4 decades. In the United States alone, the prevalence of obesity is greater than 40%, and this percentage is projected to increase past 50% by 2030. This review focuses on understanding the association between obesity and the risk of colorectal cancer while also highlighting hypotheses about molecular mechanisms underlying the link between these disease processes. We also consider whether those linkages can be disrupted via weight loss therapies, including lifestyle modifications, pharmacotherapy, bariatric surgery, and endobariatrics.

High glucose promotes the progression of colorectal cancer by activating the BMP4 signaling and inhibited by glucagon-like peptide-1 receptor agonist

BACKGROUND

The detailed molecular mechanism between type 2 diabetes mellitus (T2DM) and colorectal cancer (CRC) is still uncertain. Bone morphogenetic protein 4 (BMP4) dysregulation is implicated in T2DM and CRC, respectively. This study aims to investigate whether BMP4 can mediate the interaction of CRC with T2DM.

METHODS

We firstly explored the expression of BMP4 in The Cancer Genome Altas (TCGA) databases and CRC patients with or without DM from the Shanghai Tenth People's Hospital. The diabetic model of CRC cell lines in vitro and the mice model in vivo were developed to explore the BMP4 expression during CRC with or without diabetes. Further inhibition of BMP4 to observe its effects on CRC. Also, glucagon-like peptide-1 receptor agonist (GLP-1RA) was used to verify the underlying mechanism of hypoglycemic drugs on CRC via BMP4.

RESULTS

BMP4 expression was upregulated in CRC patients, and significantly higher in CRC patients with diabetes (P < 0.05). High glucose-induced insulin resistance (IR)-CRC cells and diabetic mice with metastasis model of CRC had increased BMP4 expression, activated BMP4-Smad1/5/8 pathway, and improved proliferative and metastatic ability mediated by epithelial-mesenchymal transition (EMT). And, treated CRC cells with exogenously BMP inhibitor-Noggin or transfected with lentivirus (sh-BMP4) could block the upregulated metastatic ability of CRC cells induced by IR. Meanwhile, GLP-1R was downregulated by high glucose-induced IR while unregulated by BMP4 inhibitor noggin, and treated GLP-1RA could suppress the proliferation of CRC cells induced by IR through downregulated BMP4.

CONCLUSIONS

BMP4 increased by high glucose promoted the EMT of CRC. The mechanism of the BMP4/Smad pathway was related to the susceptible metastasis of high glucose-induced IR-CRC. The commonly used hypoglycemic drug, GLP-1RA, inhibited the growth and promoted the apoptosis of CRC through the downregulation of BMP4. The result of our study suggested that BMP4 might serve as a therapeutic target in CRC patients with diabetes.

Crosstalk between incretin hormones, Th17 and Treg cells in inflammatory diseases

Intestinal epithelial cells constantly crosstalk with the gut microbiota and immune cells of the gut lamina propria. Enteroendocrine cells, secrete hormones, such as incretin hormones, which participate in host physiological events, such as stimulating insulin secretion, satiety, and glucose homeostasis. Interestingly, evidence suggests that the incretin pathway may influence immune cell activation. Consequently, drugs targeting the incretin hormone signaling pathway may ameliorate inflammatory diseases such as inflammatory bowel diseases, cancer, and autoimmune diseases. In this review, we discuss how these hormones may modulate two subsets of CD4 + T cells, the regulatory T cells (Treg)/Th17 axis important for gut homeostasis: thus, preventing the development and progression of inflammatory diseases. We also summarize the main experimental and clinical findings using drugs targeting the glucose-dependent insulinotropic polypeptide (GIP) and glucagon-like peptide (GLP-1) signaling pathways and their great impact on conditions in which the Treg/Th17 axis is disturbed such as inflammatory diseases and cancer. Understanding the role of incretin stimulation in immune cell activation and function, might contribute to new therapeutic designs for the treatment of inflammatory diseases, autoimmunity, and tumors.

Indication-Specific Generic Uptake of Imatinib Demonstrates the Impact of Skinny Labeling

PURPOSE

Generic competition can be delayed if brand-name manufacturers obtain additional patents on supplemental uses. The US Food and Drug Administration allows generic drug manufacturers to market versions with skinny labels that exclude patent-protected indications. This study assessed whether use of generic versions of imatinib varied between indications included and excluded from the skinny labels.

METHODS

In this cross-sectional study, we identified adult patients covered by commercial insurance or Medicare Advantage plans who initiated imatinib from February 2016 (first generic availability) to September 2020. Generic versions were introduced with skinny labels that included indications covering treatment of chronic myelogenous leukemia (CML) but excluded treatment of gastrointestinal stromal tumors (GISTs) because of remaining patent protections. Logistic regression was used to determine whether use of generic versus brand-name imatinib differed between patients with a diagnosis of CML or GIST, adjusting for demographics, insurance type, prior use of brand-name drugs, and calendar month.

RESULTS

Among 2,000 initiators, 934 (47%) had CML and 686 (34%) had GIST. Within 3 years after generics entered the market, more than 90% of initiators in both groups used generic imatinib. Initiation of generic imatinib was slightly lower among patients with GIST than among patients with CML (85% v 88%; adjusted odds ratio 0.56; 95% CI, 0.39 to 0.80; P ≤ .001).

CONCLUSION

Generic versions of imatinib were dispensed frequently for indications both included (CML) and excluded (GIST) from the skinny labeling, although patients with GIST were slightly less likely to receive a generic version. The skinny labeling pathway allowed generics to enter the market before patent protection for treating patients with GIST expired, facilitating lower drug prices.

The Regulatory Role of Neuropeptide Gene Glucagon in Colorectal Cancer: A Comprehensive Bioinformatic Analysis

Background

Colorectal cancer is highly prevalent and causes high global mortality, and glucagon axis has been implicated in colon cancer. The present study is aimed at investigating the regulating mechanisms of glucagon involvement in colorectal cancer.

Methods

Publicly available data from the TCGA database was utilized to explore the expression pattern and regulating role of glucagon (GCG) in colorectal cancer (COADREAD) including colon adenocarcinomas (COAD) and rectum adenocarcinomas (READ). Statistical analyses were performed using the R software packages and public web servers. The expression pattern and prognostic significance of GCG gene in pan-cancer and TCGA-COADREAD data were investigated by performing unpaired and paired sample analyses. The association of GCG expression with clinical characteristics was investigated using logistic regression analysis. Univariate cox regression analysis was performed to test the prognostic value of GCG expression for overall survival in COADREAD patients. GCG-significantly correlated genes were obtained. Biological functions and signaling pathways were identified by performing functional enrichment analysis and Gene Set Enrichment Analysis (GSEA). Additionally, the potential involvement of GCG in tumor immunity was researched by investigating the correlation between GCG expression and 24 tumor infiltrating immune cells.

Results

GCG was found to be significantly downregulated in COADREAD tumor samples compared with healthy control samples. GCG gene was shown to be associated with the prognostic outcomes of COADREAD, whereby its upregulation predicted improved survival outcomes. Functional enrichment analysis showed that the top 100 positively and top 100 negatively GCG-correlated genes were mainly enriched in three signaling pathways including ribosome, nitrogen metabolism, and proximal tubule bicarbonate reclamation. The GSEA showed that GCG-significantly correlated genes were mainly enriched in cell cycle-related pathways (reactome cell cycle, reactome cell cycle mitotic, reactome cell cycle checkpoints, reactome M phase, Reactome G2 M DNA damage checkpoint, and Reactome G2 M checkpoints), neuropeptide ligand receptor interaction, RHO GTPases signaling, WNT signaling, RUNX1 signaling, NOTCH signaling, ESR signaling, HCMV infection, and oxidative stress-related signaling. GCG was positively correlated with Th17 cells, pDC, macrophages, TFH cells, iDC, Tem, B cells, dendritic cells, neutrophils, mast cells, and eosinophils and was negatively associated with NK cells.

Conclusions

GCG dysregulation with high prognostic value in COADREAD was noted. Several tumor progression-related pathways and tumor immune-modulatory cells were linked to GCG expression in COADREAD. Therefore, GCG may be regarded as a potential therapeutic target for treating colorectal cancer.

Differential Risk of Cancer Associated with Glucagon-like Peptide-1 Receptor Agonists: Analysis of Real-world Databases

BACKGROUND

Glucagon-like peptide 1 receptor agonists (GLP1Ra) are commonly used in type 2 diabetes mellitus (T2DM). However, differential risk of various cancers among GLP1Ra recipients is unknown.

METHODS

We inquired an aggregated electronic health record database, Explorys, and compared the adjusted odds ratio (aOR) of cancers between GLP1Ra and metformin users. Findings were validated in the FDA Adverse Event Reporting System (FDA FAERS).

RESULTS

From 1/2005 to 6/2019, we identified 619 340 and 64 230 patients in the metformin and GLP1Ra group, respectively. Within 5 years of starting antidiabetic medications, GLP1Ra was associated with significantly lower incident risk of prostate (aOR 0.81, p = .03), lung (aOR 0.81, p = .05), and colon cancer (aOR 0.85, p = .03), while the risk of thyroid cancer was significantly higher (aOR 1.65, p < .01). Similar findings were seen in the FDA FAERS database, where GLP1Ra was associated with lower risk of prostate (aOR 0.72, p = .08), lung (aOR 0.52, p < .01), colon cancer (aOR 0.82, p = .31), and higher risk of thyroid cancer (aOR 4.33, p < .01). In addition, with longer duration of GLP1Ra use, the risk of prostate, lung, and colon cancer further decreased, suggesting an exposure duration-response relationship.

CONCLUSIONS

GLP1Ra is associated with lower risks of prostate, lung, and colon cancer, but higher risk of thyroid cancer.

Risk of cancer in patients treated with dipeptidyl peptidase-4 inhibitors: an extensive meta-analysis of randomized controlled trials

AIMS

Observational studies and meta-analyses of randomized trials on dipeptidyl peptidase-4 inhibitors (DPP4i) reported discordant results on the risk of malignancies with this class of drugs. Aim of the present meta-analysis is the assessment of the effect of DPP4i treatment on the incidence of different types of cancer, collecting all available evidence from randomized controlled trials.

METHODS

An extensive MEDLINE, EMBASE, and Cochrane database search for sitagliptin or vildagliptin or omarigliptin or saxagliptin or alogliptin or trelagliptin or anagliptin or linagliptin or gemigliptin or evogliptin or teneligliptin was performed up to September 30th, 2019. All trials performed on type 2 diabetes, with duration ≥ 24 weeks, and comparing of DPP4i with placebo or active drugs were collected. The study has been registered on PROSPERO (#153344). Mantel-Haenszel odds ratio (MH-OR) with 95% confidence interval (95% CI) was calculated for all outcomes.

RESULTS

A total of 157 eligible trials were identified. DPP-4i were not associated with an increased risk of overall cancer (MH-OR 0.93 [0.86, 1.00]; p = 0.07), with no significant differences across individual molecules of the class. When compared with placebo/none, a lower risk of cancer with DPP-4i was observed in placebo-controlled trials (MH-OR 0.90 [0.82, 0.99], p = 0.030), whereas no significant differences have been detected with any other comparators. DPP-4i was associated with a significant reduction in colorectal cancer (MH-OR 0.70 [0.53, 0.94], p = 0.020).

CONCLUSIONS

Available data do not support the hypothesis of an association of DPP4i treatment with malignancies, with a possible beneficial effect for colon-rectal cancer.

Effect of incretin-based therapies on cancers of digestive system among 101 595 patients with type 2 diabetes mellitus: a systematic review and network meta-analysis combining 84 trials with a median duration of 30 weeks

Objectives

To evaluate the risk of cancers of digestive system with incretin-based therapies among patients with type 2 diabetes mellitus.

Research design and methods

Medline, Embase, Cochrane Library and ClinicalTrials.gov databases were searched for randomized controlled clinical trials that compared incretin-based drugs with placebo or other antidiabetic drugs. Paired reviewers independently screened citations, extracted data and assessed risk of bias of included studies. Network meta-analysis was performed, followed by subgroup analysis. The Grading of Recommendations Assessment, Development and Evaluation system was used to assess the quality of evidence.

Results

A total of 84 studies (n=101 595) involving cancers of digestive system were identified (a median follow-up of 30 weeks). The risk of cancers of digestive system with incretin-based therapies was comparable with insulin (OR: 0.86, 95% CI 0.27 to 2.69), metformin (OR: 0.32, 95% CI 0.07 to 1.38), sodium-glucose co-transporter 2 (OR: 5.26, 95% CI 0.58 to 47.41), sulfonylureas (OR: 1.27, 95% CI 0.68 to 2.39), thiazolidinediones (OR: 0.42, 95% CI 0.13 to 1.42), alpha-glucosidase inhibitors (OR: 2.98, 95% CI 0.12 to 73.80), and placebo (OR: 0.87, 95% CI 0.71 to 1.05). The results of subgroup analysis based on the type of digestive system cancers indicated that incretin-based therapies did not increase the risk of gastrointestinal cancers, respectively. The results of subgroup analysis based on age, duration, mean HbA1c, trial duration, and sample size did not indicate the risk of digestive system cancers.

Conclusions

Moderate to high Grading of Recommendations Assessment, Development and Evaluation evidence suggests that incretin-based therapies were not associated with an increased risk of cancer of digestive system in patients with type 2 diabetes mellitus.

Pharmacotherapy of obesity: Available medications and drugs under investigation

Obesity is a chronic disease with a continuously rising prevalence that currently affects more than half a billion people worldwide. Energy balance and appetite are highly regulated via central and peripheral mechanisms, and weight loss triggers a homeostatic response leading to weight regain. Lifestyle and behavioral modifications are the cornerstones of obesity management; however, they often fail to achieve or sustain long-term weight loss. Pharmacotherapy added onto lifestyle modifications results in an additional, albeit limited, weight reduction. Regardless, this weight reduction of 5-10% conveys multiple cardiovascular and metabolic benefits. In this review, evidence on the food and drug administration (FDA)-approved medications, i.e., orlistat, lorcaserin, phentermine/topiramate, liraglutide and naltrexone/bupropion, is summarized. Furthermore, anti-obesity agents in the pipeline for potential future therapeutic use are presented.

Incretin-based Drugs and the Incidence of Colorectal Cancer in Patients with Type 2 Diabetes

BACKGROUND

Evidence on the safety of the incretin-based drugs (glucagon-like peptide-1 [GLP-1] analogues and dipeptidyl peptidase-4 [DPP-4] inhibitors) with respect to colorectal cancer is contradictory. The objective of this study was to determine whether use of incretin-based drugs is associated with risk of incident colorectal cancer in patients with type 2 diabetes.

METHODS

Using data from the UK Clinical Practice Research Datalink, we identified a cohort of 112,040 patients newly treated with antidiabetic drugs between 1 January 2007 and 31 March 2015. We modeled use of GLP-1 analogues and DPP-4 inhibitors as time-varying variables and compared them with use of sulfonylureas. We lagged exposures by 1 year for latency and to reduce reverse causality and detection bias. We used time-dependent Cox proportional hazards models to estimate hazard ratios with 95% confidence intervals of incident colorectal cancer associated with the use of GLP-1 analogues and DPP-4 inhibitors overall, by cumulative duration of use and by time since initiation.

RESULTS

During 388,619 person-years of follow-up, there were 733 incident colorectal cancer events (incidence rate: 1.9 per 1,000 person-years). Use of GLP-1 analogues was not associated with colorectal cancer incidence (hazard ratio: 1.0; 95% confidence interval = 0.7, 1.6), nor was use of DPP-4 inhibitors (hazard ratio: 1.2; 95% confidence interval = 1.0, 1.5). There was no evidence of a duration-response relation for either drug.

CONCLUSIONS

The results of this large population-based study indicate that use of incretin-based drugs is not associated with colorectal cancer incidence among patients with type 2 diabetes.

Neoplasms Reported With Liraglutide or Placebo in People With Type 2 Diabetes: Results From the LEADER Randomized Trial

OBJECTIVE

This study explored neoplasm risk with liraglutide versus placebo in the LEADER (Liraglutide Effect and Action in Diabetes: Evaluation of Cardiovascular Outcome Results) cohort.

RESEARCH DESIGN AND METHODS

LEADER (NCT01179048) was an international, phase 3b, randomized, double-blind, controlled trial. Participants aged ≥50 years with type 2 diabetes and high cardiovascular risk were assigned 1:1 to receive liraglutide (≤1.8 mg daily; n = 4,668) or placebo (n = 4,672) in addition to standard care and monitored for 3.5-5 years (median follow-up 3.8 years). The occurrence of neoplasms was a prespecified, exploratory secondary end point. Post hoc analyses of the time to the first confirmed neoplasms were conducted using a Cox regression model.

RESULTS

Neoplasm was confirmed in 10.1% of patients with liraglutide versus 9.0% with placebo (hazard ratio [HR] 1.12 [95% CI 0.99; 1.28]). The HR (95% CI) for liraglutide versus placebo was 1.06 (0.90; 1.25) for malignant neoplasms and 1.16 (0.93; 1.44) for benign neoplasms. Sensitivity analyses excluding neoplasms occurring <1 year or <2 years after randomization and analyses by sex provided similar results. In our main analyses, the 95% CI for the HR included one for all malignant neoplasms evaluated (including pancreatic and thyroid neoplasms) except for prostate neoplasms, which occurred in fewer liraglutide-treated patients.

CONCLUSIONS

LEADER was not primarily designed to assess neoplasm risk. Firm conclusions cannot be made regarding numeric imbalances observed for individual neoplasm types (e.g., pancreatic cancer) that occurred infrequently. LEADER data do, however, exclude a major increase in the risk of total malignant neoplasms with liraglutide versus placebo. Additional studies are needed to assess longer-term exposure.

Risk of dipeptidyl peptidase-4 (DPP-4) inhibitors on site-specific cancer: A systematic review and meta-analysis

The long-term impact of dipeptidyl peptidase-4 (DPP-4) inhibition is unknown, and there are concerns about the influence of DPP-4 inhibition on carcinogenesis of the pancreas and thyroid. As DPP-4 is a rather unselective enzyme present in many tissues, we focused on all specific cancer types. PubMed and EMBASE were searched between January 2005 and April 2017 to identify studies comparing DPP-4 inhibitors with either placebo or active drugs on cancer risk. Studies were included if they reported on at least one specific cancer outcome and had a follow-up of at least 1 year after start of drug use. Methodological quality of the studies was assessed by the Cochrane Collaboration's tool and the Newcastle-Ottawa Scale. Twenty-five studies met the inclusion criteria (12 randomized controlled trials and 13 observational studies). Sample sizes of the DPP-4 inhibitor groups ranged from 29 to 8212 patients for randomized controlled trials and from 2422 to 71 137 patients for observational studies. Mean age ranged from 51 to 76 years, and mean follow-up was 1.5 years. None of the pooled (sensitivity) analyses, except the observational studies studying breast cancer (hazard ratio [95% CI]: 0.76 [0.60-0.96]), showed evidence for an association between DPP-4 inhibitors and site-specific cancer. Also for pancreatic and thyroid cancer, no statistically significant risk was found. Based on the current literature, it is not possible to conclude whether DPP-4 inhibitors were associated with an increased risk of site-specific cancer. Future studies should address the methodological limitations and follow patients for a longer period to determine the long-term cancer risk of DPP-4 inhibitors.

Thiazolidinediones and risk of colorectal cancer in patients with diabetes mellitus: A meta-analysis

BACKGROUND/AIMS

A growing body of evidence has suggested that thiazolidinediones (TZDs) potentially reduce the risk of colorectal cancer (CRC). This study aimed to evaluate the effect of TZDs on CRC risk in patients with diabetes mellitus (DM).

PATIENTS AND METHODS

A systematic search of electronic databases was performed for studies evaluating the exposure to TZDs and reporting CRC risk in diabetic patients. Pooled estimates with 95% confidence intervals (CIs) were estimated using fixed or random effects models.

RESULTS

A total of 10 observational studies reporting more than 18,972 CRC cases in 2,470,768 DM patients were included. Meta-analysis showed a 9% reduction in CRC risk associated with TZDs use in all studies [relative risk (RR) =0.91, 95% CI = 0.84-0.99, P = 0.03] and cohort studies (RR = 0.89, 95% CI = 0.80-0.99, P = 0.04), respectively. However, such effect was not shown in case-control studies. In subgroup analyses, lower CRC risk was found in Asian population (RR = 0.40, 95% CI = 0.29-0.53, P = 0.00), and a trend toward lower CRC risk was observed in US population (RR = 0.94, 95% CI = 0.88-1.01, P = 0.08). CRC risk was significantly modified with non-pioglitazone TZD use (RR = 0.88, 95% CI = 0.82-0.95, P = 0.00), but not with pioglitazone use (RR = 0.95, 95% CI = 0.89-1.01, P = 0.11). No significant difference was observed with cancer site (colon or rectum). There was considerable inherent heterogeneity across studies, partly explained by study location.

CONCLUSIONS

This meta-analysis supports a protective association between TZDs use and CRC risk in patients with DM. Future well-designed prospective studies with larger cohorts would be needed to understand this association better.

Diabetes drugs and the incidence of solid cancers: a survey of the current evidence

INTRODUCTION

The evaluation of the relationship between the use of antidiabetic drug and the occurrence of cancer is extremely challenging, both from the clinical and pharmacoepidemiological standpoint. This narrative review described the current evidence supporting a relationship between the use of antidiabetic drugs and the incidence of solid cancers. Areas covered: Data from pharmacoepidemiological studies on cancer incidence were presented for the main antidiabetic drugs and drug classes, including human insulin and insulin analogues, metformin, sulfonylureas, glinides, alpha-glucosidase inhibitors, thiazolidinediones, incretin mimetics, and sodium glucose co-transporter 2 inhibitors. The relationship between the use of antidiabetics and the incidence of solid cancer was described in strata by any cancer and by organ-specific cancer and by drug and by drug classes. Information supporting biological evidence and putative mechanisms were also provided. Expert opinion: The history of exploration of the relationship between antidiabetic drugs and the risk of solid cancers has showed several issues. Unrecognized biases and misinterpretations of study results have had important consequences that delayed the identification of actual risk and benefits of the use of antidiabetic drugs associated with cancer occurrence or progression. The lesson learned from the past should address the future research in this area, since in the majority of cases findings are controversial and confirmatory studies are warranted.