Diabetes, insulin use, and gastric cancer: a population-based analysis of the Taiwanese

Acarbose might be associated with reduced risk of gastric cancer in patients with diabetes mellitus: A nationwide population-based cohort study

BACKGROUND

Several epidemiologic studies have revealed a higher risk of cancer in patients with diabetes mellitus (DM) relative to the general population. To investigate whether the use of acarbose was associated with higher/lower risk of new-onset cancers.

METHOD

We conducted a retrospective cohort study, using a population-based National Health Insurance Research Database of Taiwan. Both inpatients and outpatients with newly onset DM diagnosed between 2000 and 2012 were collected. The Adapted Diabetes Complications Severity Index (aDCSI) was used to adjust the severity of DM. The Cox proportional hazards regression model was used to estimate the hazard ratio (HR) of disease.

RESULTS

A total of 22 502 patients with newly diagnosed DM were enrolled. The Cox proportional hazards regression model indicating acarbose was neutral for risk for gastroenterological malignancies, when compared to the acarbose non-acarbose users group. However, when gastric cancer was focused, acarbose-user group had significantly lowered HR than non-acarbose users group (p = 0.003). After adjusted for age, sex, cancer-related comorbidity, severity of DM, and co-administered drugs, the HR of gastric cancer risk was 0.43 (95% CI = 0.25-0.74) for acarbose-user patients.

CONCLUSION

This long-term population-based study demonstrated that acarbose might be associated with lowered risk of new-onset gastric cancer in diabetic patients after adjusting the severity of DM.

Metformin suppresses gastric cancer progression by disrupting the STAT1-PRMT1 axis

Gastric cancer (GC) is a common form of cancer and the leading cause of cancer-related deaths worldwide. Chemotherapy is the primary treatment for patients with unresectable or partially resectable GC. However, its adverse effects and chemoresistance greatly restrict its applicability and efficacy. Although HER2-targeted therapy and immunotherapy have been successfully used for GC treatment, their beneficial population is limited. To expand the range of cancer treatments, drug repurposing has emerged as a promising strategy. In this study, we evaluated the potential of Metformin, an oral anti-hyperglycemic agent, to suppress GC progression both in vivo and in vitro. Functional investigations showed that Metformin significantly inhibits GC proliferation and migration. Furthermore, we discovered that Metformin bound and disrupted STAT1 phosphorylation, inhibiting PRMT1 expression and consequently GC progression. In conclusion, our study not only provides further evidence for the anti-GC role of Metformin but also identifies the direct target mediating the tumor-inhibitory effects of Metformin in GC.

The causal relationship between anti-diabetic drugs and gastrointestinal disorders: a drug-targeted mendelian randomization study

BACKGROUND

The incidence of diabetic gastrointestinal diseases is increasing year by year. This study aimed to investigate the causal relationship between antidiabetic medications and gastrointestinal disorders, with the goal of reducing the incidence of diabetes-related gastrointestinal diseases and exploring the potential repurposing of antidiabetic drugs.

METHODS

We employed a two-sample Mendelian randomization (TSMR) design to investigate the causal association between antidiabetic medications and gastrointestinal disorders, including gastroesophageal reflux disease (GERD), gastric ulcer (GU), chronic gastritis, acute gastritis, Helicobacter pylori infection, gastric cancer (GC), functional dyspepsia (FD), irritable bowel syndrome (IBS), ulcerative colitis (UC), Crohn's disease (CD), diverticulosis, and colorectal cancer (CRC). To identify potential inhibitors of antidiabetic drug targets, we collected single-nucleotide polymorphisms (SNPs) associated with metformin, GLP-1 receptor agonists, SGLT2 inhibitors, DPP-4 inhibitors, insulin, and its analogs, thiazolidinediones, sulfonylureas, and alpha-glucosidase inhibitors from published genome-wide association study statistics. We then conducted a drug-target Mendelian randomization (MR) analysis using inverse variance weighting (IVW) as the primary analytical method to assess the impact of these inhibitors on gastrointestinal disorders. Additionally, diabetes was selected as a positive control.

RESULTS

Sulfonylureas were found to significantly reduce the risk of CD (IVW: OR [95% CI] = 0.986 [0.978, 0.995], p = 1.99 × 10- 3), GERD (IVW: OR [95% CI] = 0.649 [0.452, 0.932], p = 1.90 × 10- 2), and chronic gastritis (IVW: OR [95% CI] = 0.991 [0.982, 0.999], p = 4.50 × 10- 2). However, they were associated with an increased risk of GU development (IVW: OR [95%CI] = 2 0.761 [1.259, 6.057], p = 1 0.12 × 10- 2).

CONCLUSIONS

The results indicated that sulfonylureas had a positive effect on the prevention of CD, GERD, and chronic gastritis but a negative effect on the development of gastric ulcers. However, our research found no causal evidence for the impact of metformin, GLP-1 agonists, SGLT2 inhibitors, DPP 4 inhibitors, insulin and its analogs, thiazolidinediones, or alpha-glucosidase inhibitors on gastrointestinal diseases.

Diabetes Mellitus and Gastric Cancer: Correlation and Potential Mechanisms

This review summarizes the correlation between diabetes mellitus (DM) and gastric cancer (GC) from the perspectives of epidemiology, drug use, and potential mechanisms. The association between DM and GC is inconclusive, and the positive direction of the association reported in most published meta-analyses suggests that DM may be an independent risk factor for GC. Many clinical investigations have shown that people with DM and GC who undergo gastrectomy may have better glycemic control. The potential link between DM and GC may involve the interaction of multiple common risk factors, such as obesity, hyperglycemia and hyperinsulinemia, H. pylori infection, and the use of metformin. Although in vitro and in vivo data support that H. pylori infection status and metformin can influence GC risk in DM patients, there are conflicting results. Patient survival outcomes are influenced by multiple factors, so further research is needed to identify the patients who may benefit.

Prognostic value of long-term antidiabetic and antihypertensive therapy in postoperative gastric cancer patients: the FIESTA study

Background

Gastric cancer is often comorbid with hypertension and diabetes mellitus and increases the mortality risk.

Materials and methods

We conducted this prospective cohort study to investigate antidiabetics and antihypertensives’ impact on gastric cancer survival. 3012 patients with gastric carcinoma undergoing radical gastrectomy were enrolled since January 2000 and followed up until July 2020.

Results

Hypertension and diabetes patients had worse survival than patients without hypertension and diabetes [median survival time (MST): 48 versus 112.5 months, p < 0.001 for hypertension, MST: 32.7 versus 183+ months, p < 0.001 for diabetes]. Compared to untreated patients, treated patients had better survival (MST: 109.7 months versus 39.1 months, p < 0.001 for antihypertensives, MST: 120.9 months versus 22.3 months, p < 0.001 for antidiabetics). Antihypertensives and antidiabetics were related to 42% (HR 0.58, 95% CI 0.47–0.73, p < 0.001) and 70% (HR 0.30, 95% CI 0.24–0.38, p < 0.001) reduced mortality risk relative to those without medications. metformin and Calcium channel blockers can better-improved prognosis compared to others (p = 0.00029 and p = 0.015).

Conclusion

Post-surgical gastric cancer patients could benefit substantially from anti-diabetes and antihypertensive therapy. Metformin and Calcium channel blockers may be superior to other medications.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12876-022-02514-4.

Influence of Fasting Glucose Level on Gastric Cancer Incidence in a Prospective Cohort Study

BACKGROUND

High fasting glucose has been indicated in relation to a higher risk of gastric cancer, but the majority of studies have focused on diabetes (fasting glucose ≥126 mg/dL). Here, we investigated whether fasting glucose levels, including prediabetic and diabetic levels, influence gastric cancer incidence.

METHODS

A prospective study was conducted with 41,837 participants aged 16 and older who underwent health examinations at the National Cancer Center in South Korea from August 2002 to December 2014. Participants were followed up until December 2017 to identify incident gastric cancer cases. A fasting glucose test was performed based on venous blood samples taken from participants after 8 hours of fasting. We used the Cox proportional hazards regression model to explore the association of fasting glucose levels with gastric cancer incidence.

RESULTS

We identified 263 incident gastric cancer cases during the follow-up period. A significant association of high fasting glucose with gastric cancer incidence was found for postmenopausal women [hazard ratio (HR) = 1.88; 95% confidence interval (CI) = 1.11-3.20]. There was also a significant association between high fasting glucose and gastric cancer incidence among all participants who were nonsmokers (HR = 1.89; 95% CI = 1.21-2.95), had a BMI < 25 kg/m² (HR = 1.45; 95% CI = 1.00-2.12), and did not have a first-degree family history of gastric cancer (HR = 1.45; 95% CI = 1.06-1.99).

CONCLUSIONS

Our findings support that high fasting glucose is a risk factor for gastric cancer development in postmenopausal women.

IMPACT

Our results provide evidence for future planning and management regarding cancer prevention.

The Relationship between Diabetes Mellitus and Gastric Cancer and the Potential Benefits of Metformin: An Extensive Review of the Literature

The objective of this review is to summarize the findings of published research that investigated the relationship between diabetes mellitus and gastric cancer (GCa) and the potential benefits of metformin on GCa. Related literature has been extensively reviewed, and findings from studies investigating the relationship between diabetes mellitus and GCa suggest that hyperglycemia, hyperinsulinemia and insulin resistance are closely related to the development of GCa. Although not supported by all, most observational studies suggest an increased risk of GCa in patients with type 2 diabetes mellitus, especially in women and in Asian populations. Incidence of second primary malignancy diagnosed after GCa is significantly higher in diabetes patients. Diabetes patients with GCa may have more complications after gastrectomy or chemotherapy and they may have a poorer prognosis than patients with GCa but without diabetes mellitus. However, glycemic control may improve in the diabetes patients with GCa after receiving gastrectomy, especially after procedures that bypass the duodenum and proximal jejunum, such as Roux-en-Y gastric bypass or Billroth II reconstruction. The potential links between diabetes mellitus and GCa may involve the interactions with shared risk factors (e.g., obesity, hyperglycemia, hyperinsulinemia, insulin resistance, high salt intake, smoking, etc.), Helicobacter pylori (HP) infection, medications (e.g., insulin, metformin, statins, aspirin, proton pump inhibitors, antibiotics, etc.) and comorbidities (e.g., hypertension, dyslipidemia, vascular complications, heart failure, renal failure, etc.). With regards to the potential benefits of metformin on GCa, results of most observational studies suggest a reduced risk of GCa associated with metformin use in patients with T2DM, which can be supported by evidence derived from many in vitro and animal studies. Metformin use may also reduce the risk of HP infection, an important risk factor of GCa. In patients with GCa, metformin users may have improved survival and reduced recurrence. More studies are required to clarify the pathological subtypes/anatomical sites of GCa associated with type 2 diabetes mellitus or prevented by metformin, to confirm whether GCa risk can also be increased in patients with type 1 diabetes mellitus and to explore the possible role of gastric microbiota in the development of GCa.

Insulin enhances and metformin reduces risk of colorectal carcinoma in type-2 diabetes

BACKGROUND

Identifying colorectal cancer associated risks is important for conducting a program for the survey and prevention of colorectal cancer.

AIM

To investigate the association between use of insulin or metformin with colorectal cancer (CRC) in type 2 diabetes (T2DM).

DESIGN

Population-based cohort study.

METHODS

Through analysis of National Health Insurance (NHI) database between 1998 and 2010 in Taiwan, we identified 66 324 T2DM patients aged ≥ 20 years and selected subjects without diabetes by 1: 1 randomly matching with the study cohort based on age, sex and index date. We followed up the participants until 31 December 2011 or when they withdrew from the NHI program.

RESULTS

Compared with non-diabetic subjects, the T2DM patients exhibited an increased risk of CRC [adjusted HR (aHR) = 1.56, 95% confidence interval (CI) = 1.39-1.75], after adjustment for age, sex, urbanization level, comorbidities and examinations of colonoscopy, sigmoidoscopy, or stool occult blood test. Among the T2DM patients, insulin usage increased the risk of CRC (aHR = 1.86, 95% CI = 1.58-0-2.19) after adjustment for age, sex, urbanization level, comorbidities, metformin usage and examinations; nevertheless, metformin decreased the risk of CRC (aHR = 0.65, 95% CI = 0.54-0.77) after adjustment for age, sex, urbanization level, comorbidities, insulin usage and examinations. Compared with the non-insulin cohort, the risk of CRC tended to increase with the incremental dosage of insulin exposure.

CONCLUSION

Our population-based cohort study demonstrated an association between T2DM and CRC. Among the T2DM patients, insulin use was associated with an increased risk of CRC and metformin use was associated with a decreased risk of CRC. Inability to obtain information on several potential confounding factors, such as lifestyle and dietary habits, is the major limitation of the study.

Diabetes mellitus and the risk of gastric cancer: a meta-analysis of cohort studies

Studies examining the relationship between diabetes mellitus (DM) and the risk of gastric cancer incidence or gastric cancer mortality have produced inconsistent results. The purpose of this study was to evaluate the evidence regarding the relationship between DM and subsequent gastric cancer incidence or gastric cancer mortality risk on the basis of cohort studies. A systematic search of articles in PubMed, EmBase, the Cochrane Library, and reference lists was conducted to identify relevant literature. Twenty-two cohort studies reporting data on 8,559,861 participants were included in the study. Overall, participants with DM had little or no change in the risk of gastric cancer, or gastric cancer mortality. There was no evidence of difference in the RR for gastric cancer between men and women. Participants with DM had a non-significant trend towards an increased risk of gastric cancer mortality in men. There was no significant difference between men and women for this relationship. Finally, although subgroup analysis suggested DM was associated with a significant impact on gastric cancer incidence and gastric cancer mortality risk in several specific populations, a significance based on gender difference was not observed. In conclusion, DM might increase the risk of gastric cancer in men when the study used standard incidence/mortality ratio as effect estimate. Further, DM were associated with higher risk of gastric cancer mortality in men if the mean age at baseline less than 55.0 years, used RR or HR as effect estimate, the study adjusted smoking or not, and the study not adjusted alcohol drinking.

Sex hormone-binding globulin (SHBG) is a potential early diagnostic biomarker for gastric cancer

The use of blood plasma biomarkers in gastric cancer (GC) management is limited due to a lack of reliable biomarkers. An LC-MS/MS assay and a bioinformatic analysis were performed to identify blood plasma biomarkers in a GC discovery cohort. The data obtained were verified and validated by western blotting and an ELISA in an independent study cohort. A label-free quantification analysis of the MS data using PEAKS7 software found that four plasma proteins of apolipoprotein C-1, gelsolin, sex hormone-binding globulin (SHBG), and complement component C4-A were significantly overexpressed in GC patients. A western blot assay of these plasma proteins showed that only SHBG was consistently overexpressed in the patient group. ELISA measurement of SHBG blood plasma levels confirmed that the patient group had significantly higher SHBG levels than the control group. SHBG levels in the patient group remained significantly higher after being stratified by gender, age, and disease stage. These findings show that LC-MS/MS is powerful and highly sensitive for plasma biomarker discovery, and SHBG could be a potential plasma biomarker for GC management.

Male non-insulin users with type 2 diabetes mellitus are predisposed to gastric corpus-predominant inflammation after H. pylori infection

BACKGROUND

Both H. pylori infection and diabetes increase the risk of gastric cancer. This study investigated whether patients with type 2 diabetes mellitus (T2DM) and H. pylori infection had more severe corpus gastric inflammation and higher prevalence of precancerous lesions than non-diabetic controls.

METHODS

A total of 797 patients with type 2 diabetes mellitus were screened for H. pylori, of whom 264 had H. pylori infection. Of these patients, 129 received esophagogastroduodenoscopy to obtain topographic gastric specimens for gastric histology according to the modified Updated Sydney System, corpus-predominant gastritis index (CGI), Operative Link on Gastritis Assessment, and Operative Link on Gastric Intestinal Metaplasia Assessment. Non-diabetic dyspeptic patients who had H. pylori infection confirmed by esophagogastroduodenoscopy were enrolled as controls.

RESULTS

The male as well as total T2DM patients had higher acute/chronic inflammatory and lymphoid follicle scores in the corpus than non-diabetic controls (p < 0.05). In contrast, the female T2DM patients had higher chronic inflammatory scores in the antrum than the controls (p < 0.05). In T2DM patients, the males had significantly higher rates of CGI than the females (p < 0.05). Multivariate logistic regression analysis showed that male patients (odds ratio: 2.28, 95% confidence interval: 1.11-4.69, p = 0.025) and non-insulin users (odds ratio: 0.33, 95% confidence interval: 0.15-0.74, p = 0.007) were independent factors for the presence of CGI in the H. pylori-infected patients with type 2 diabetes mellitus.

CONCLUSIONS

Patients with type 2 diabetes mellitus and H. pylori infection had more severe corpus gastric inflammation than non-diabetic controls. Moreover, male gender and non-insulin users of T2DM patients were predisposed to have corpus-predominant gastritis after H. pylori infection.

TRIAL REGISTRATION

ClinicalTrial: NCT02466919 , retrospectively registered may 17, 2015.

Risk of stomach cancer in Aotearoa/New Zealand: A Māori population based case-control study

Māori, the indigenous people of New Zealand, experience disproportionate rates of stomach cancer, compared to non-Māori. The overall aim of the study was to better understand the reasons for the considerable excess of stomach cancer in Māori and to identify priorities for prevention. Māori stomach cancer cases from the New Zealand Cancer Registry between 1 February 2009 and 31 October 2013 and Māori controls, randomly selected from the New Zealand electoral roll were matched by 5-year age bands to cases. Logistic regression was used to estimate odd ratios (OR) and 95% confidence intervals (CI) between exposures and stomach cancer risk. Post-stratification weighting of controls was used to account for differential non-response by deprivation category. The study comprised 165 cases and 480 controls. Nearly half (47.9%) of cases were of the diffuse subtype. There were differences in the distribution of risk factors between cases and controls. Of interest were the strong relationships seen with increased stomach risk and having >2 people sharing a bedroom in childhood (OR 3.30, 95%CI 1.95–5.59), testing for H pylori (OR 12.17, 95%CI 6.15–24.08), being an ex-smoker (OR 2.26, 95%CI 1.44–3.54) and exposure to environmental tobacco smoke in adulthood (OR 3.29, 95%CI 1.94–5.59). Some results were attenuated following post-stratification weighting. This is the first national study of stomach cancer in any indigenous population and the first Māori-only population-based study of stomach cancer undertaken in New Zealand. We emphasize caution in interpreting the findings given the possibility of selection bias. Population-level strategies to reduce the incidence of stomach cancer in Māori include expanding measures to screen and treat those infected with H pylori and a continued policy focus on reducing tobacco consumption and uptake.

Association between metformin and the risk of gastric cancer in patients with type 2 diabetes mellitus: a meta-analysis of cohort studies

Objectives

The objective of this study was to evaluate the association between metformin therapy and the incidence of gastric cancer (GC) in patients with type 2 diabetes mellitus (T2DM).

Methods

We systemically searched the following databases for studies published between the databases’ dates of inception and Nov. 2016: PubMed, Embase, the Cochrane Library, the Web of Science, and the China National Knowledge Infrastructure (CNKI). Hazard ratios (HR)and corresponding 95% confidence intervals (CIs) for the association between metformin therapy and the incidence of GC in patients with T2DM were the outcome measures assessed in this study. STATA 12.0 (Stata Corporation, College Station, Texas, USA) was used to conduct the statistical analysis.

Results

A total of seven cohort studies including 591,077 patients met all the criteria for inclusion in the analysis. Our data showed that metformin therapy was associated with a significantly lower incidence of GC in patients with T2DM than other types of therapy (HR=0.763, 95% CI: 0.642˜0.905). Subgroup analysis showed that patients living in Taiwan benefitted more from metformin therapy than patients living in any other region, as metformin significantly decreased the risk of GC in patients living in Taiwan but did not significantly decrease the risk of GC in patients living in other regions (HR=0.514, 95% CI: 0.384-0.688). The results of the present analysis support the idea that metformin facilitates reductions in the risk of T2DM-related GC.

Conclusions

The risk of GC among patients with T2DM is lower in patients receiving metformin therapy than in patients not receiving metformin therapy.

An Elevated HbA1c Level Is Associated With Short-Term Adverse Outcomes in Patients With Gastrointestinal Cancer and Type 2 Diabetes Mellitus

Background

Although an elevated hemoglobin A1c (HbAc1) level is an independent predictor of worse survival in patients with both digestive cancer and diabetes mellitus, its relationship to short-term prognosis in these patients has not been addressed. This study assessed this relationship in gastrointestinal cancer (GIC) patients with type 2 diabetes mellitus (T2DM).

Methods

A retrospective review of patients with GIC with or without T2DM from 2004 to 2014 was performed. Patients with T2DM were grouped according to HbA1c level, either normal (mean < 7.0%) or elevated (mean ≥ 7.0%). Age- and sex-matched GIC patients without T2DM served as controls.

Results

One hundred and eighteen patients aged 33 - 81 years with T2DM met the study eligibility criteria; 51 were in the normal HbA1c group, and 67 were in the elevated HbA1c group. The 91 patients in the non-T2DM group were randomly selected and matched to the T2DM group in terms of admittance date, age, and sex. There was a trend toward a higher 180-day mortality rate in the T2DM group compared with the non-T2DM group (15.3% vs. 7.7%, P = 0.095) and in the elevated HbA1c group compared with the normal HbA1c group (19.4% vs. 9.8%, P = 0.151); however, the differences were not significant. The duration of the hospital stay was longer in patients with T2DM than in those without T2DM (13.2 vs. 8.9 days, P < 0.05) and in patients with elevated versus normal HbA1c levels (14.5 vs. 11.4 days, P < 0.05). Diabetic GIC patients with elevated HbA1c levels had significantly more total postoperative complications than those with normal HbA1c levels (25.4% vs. 9.8%, P < 0.05). In multivariate regression analyses, short-term adverse outcomes were strongly associated with elevated HbA1c levels (odds ratio (OR): 5.276; 95% confidence level (CI): 1.73 - 16.095; P < 0.05) and no strict antidiabetic treatment (OR: 7.65; 95% CI: 2.49 - 23.54; P < 0.001).

Conclusion

An elevated level of HbA1c significantly correlated with and was an independent predictor of short-term adverse outcomes in GIC patients with T2DM.

Metformin reduces gastric cancer risk in patients with type 2 diabetes mellitus

This retrospective cohort study investigated whether metformin may reduce gastric cancer risk by using the reimbursement databases of the Taiwan's National Health Insurance. Patients with type 2 diabetes diagnosed during 1999-2005 and newly treated with metformin (n=287971, "ever users of metformin") or other antidiabetic drugs (n=16217, "never users of metformin") were followed until December 31, 2011. The effect of metformin (for ever versus never users, and for tertiles of cumulative duration of therapy) was estimated by Cox regression incorporated with the inverse probability of treatment weighting using propensity score. Results showed that the respective numbers of incident gastric cancer in ever and never users were 759 (0.26%) and 89 (0.55%), with respective incidences of 55.26 and 122.53 per 100,000 person-years. The overall hazard ratio (95% confidence intervals) of 0.448 (0.359-0.558) suggested a significantly lower risk among ever users. In tertile analyses, hazard ratios (95% confidence intervals) for the first (＜21.47 months), second (21.47-45.97 months) and third (＞45.97 months) tertile of cumulative duration was 0.973 (0.773-1.224), 0.422 (0.331-0.537) and 0.120 (0.090-0.161), respectively, while compared to never users. In conclusion, metformin significantly reduces gastric cancer risk, especially when the cumulative duration is more than approximately 2 years.

Hyperglycemia Promotes Human Gastric Carcinoma Progression via Aquaporin 3

BACKGROUND

Hyperglycemia plays an important role in the development of gastric carcinoma (GC). Aquaporin 3 (AQP3) is overexpressed in GC and involved in carcinogenesis and progression of GC. Hyperglycemia promotes AQP3 expression in human peritoneal mesothelial cells.

AIMS

To investigate whether hyperglycemia promotes progression of GC via AQP3.

METHODS

We enrolled 978 patients with GC and evaluated the correlation between preoperative fasting plasma glucose and clinicopathological features. AQP3 was detected by immunohistochemistry in human GC specimens. Western blotting and real-time quantitative polymerase chain reaction evaluated changes in AQP3 expression in human GC MGC803 and SGC7901 cells after co-culture with high glucose. Transwell migration and Cell Counting Kit-8 assays were used to determine migration and proliferation of GC cells.

RESULTS

Hyperglycemia (fasting plasma glucose ≥6.1 mM) correlated with tumor size, location, and pTNM stage. AQP3 expression in tumor tissue was associated with fasting plasma glucose levels. High glucose concentration upregulated AQP3 expression in a dose- and time-dependent manner. High glucose concentration promoted GC cell migration markedly, and AQP3 knockdown with siRNA could abolish the increase in cell migration. However, high glucose concentration inhibited cell proliferation, and AQP3 knockdown significantly enhanced the inhibitory effect of high glucose. The ERK and PI3K/AKT signaling pathways were involved in high glucose regulation of AQP3 in human GC cells.

CONCLUSION

Hyperglycemia promotes GC progress via AQP3. This improves our understanding of the mechanism of hyperglycemia-induced carcinogenesis and provides a potential therapeutic strategy for GC.

Diabetes but not insulin increases the risk of lung cancer: a Taiwanese population-based study

Background

The trend of lung cancer incidence in Taiwan is unknown, and the association between type 2 diabetes/insulin use and lung cancer is rarely studied.

Methods

The trends of lung cancer incidence in 1979–2007 in the Taiwanese general population were calculated. A random sample of 1,000,000 subjects covered by the National Health Insurance in 2005 was recruited. A total of 494,002 men and 502,948 women and without lung cancer were followed for the annual cumulative incidence of lung cancer in 2005, with calculation of the risk ratios between diabetic and non-diabetic subjects. Logistic regression estimated the adjusted odds ratios for risk factors.

Results

The trends increased significantly in both sexes (P<0.0001). The sex-specific annual cumulative incidence increased with age in either the diabetic or non-diabetic subjects, but the risk ratios attenuated with age. In logistic regressions, diabetes was associated with a significantly higher risk, with odds ratios (95% confidence interval) for diabetes duration <1, 1–3, 3–5 and ≥5 years versus non-diabetes of 2.189 (1.498-3.200), 1.420 (1.014-1.988), 1.545 (1.132-2.109), and 1.329 (1.063-1.660), respectively. Such an association was not related to a higher detection with chest X-ray examination. Insulin use and medications including oral anti-diabetic drugs, statin, fibrate, and anti-hypertensive agents were not significantly associated with lung cancer. Age, male sex, and chronic obstructive pulmonary disease were positively; but dyslipidemia, stroke and higher socioeconomic status were negatively associated with lung cancer.

Conclusions

Diabetes is significantly associated with a higher risk of lung cancer, but insulin use does not increase the risk.

Diabetes and gastric cancer: The potential links

This article reviews the epidemiological evidence linking diabetes and gastric cancer and discusses some of the potential mechanisms, confounders and biases in the evaluation of such an association. Findings from four meta-analyses published from 2011 to 2013 suggest a positive link, which may be more remarkable in females and in the Asian populations. Putative mechanisms may involve shared risk factors, hyperglycemia, Helicobacter pylori (H. pylori) infection, high salt intake, medications and comorbidities. Diabetes may increase the risk of gastric cancer through shared risk factors including obesity, insulin resistance, hyperinsulinemia and smoking. Hyperglycemia, even before the clinical diagnosis of diabetes, may predict gastric cancer in some epidemiological studies, which is supported by in vitro, and in vivo studies. Patients with diabetes may also have a higher risk of gastric cancer through the higher infection rate, lower eradication rate and higher reinfection rate of H. pylori. High salt intake can act synergistically with H. pylori infection in the induction of gastric cancer. Whether a higher risk of gastric cancer in patients with diabetes may be ascribed to a higher intake of salt due to the loss of taste sensation awaits further investigation. The use of medications such as insulin, metformin, sulfonylureas, aspirin, statins and antibiotics may also influence the risk of gastric cancer, but most of them have not been extensively studied. Comorbidities may affect the development of gastric cancer through the use of medications and changes in lifestyle, dietary intake, and the metabolism of drugs. Finally, a potential detection bias related to gastrointestinal symptoms more commonly seen in patients with diabetes and with multiple comorbidities should be pointed out. Taking into account the inconsistent findings and the potential confounders and detection bias in previous epidemiological studies, it is expected that there are still more to be explored for the clarification of the association between diabetes and gastric cancer.

A review on thiazolidinediones and bladder cancer in human studies

There is a concern of an increased risk of bladder cancer associated with the use of thiazolidinediones, a class of oral glucose-lowering drugs commonly used in patients with type 2 diabetes with a mechanism of improving insulin resistance. Human studies on related issues are reviewed, followed by a discussion on potential concerns on the causal inference in current studies. Pioglitazone and rosiglitazone are discussed separately, and findings from different geographical regions are presented. Randomized controlled trials designed for primarily answering such a cancer link are lacking, and evidence from clinical trials with available data for evaluating the association may not be informative. Observational studies have been reported with the use of population-based administrative databases, single-hospital records, drug adverse event reporting system, and case series collection. Meta-analysis has also been performed by six different groups of investigators. These studies showed a signal of higher risk of bladder cancer associated with pioglitazone, especially at a higher cumulative dose or after prolonged exposure; however, a weaker signal or null association is observed with rosiglitazone. In addition, there are some concerns on the causal inference, which may be related to the use of secondary databases, biases in sampling, differential detection, and confounding by indications. Lack of full control of smoking and potential biases related to study designs and statistical approaches such as prevalent user bias and immortal time bias may be major limitations in some studies. Overlapping populations and opposing conclusions in studies using the same databases may be of concern and weaken the reported conclusions of the studies. Because randomized controlled trials are expensive and unethical in providing an answer to this cancer issue, observational studies are expected to be the main source in providing an answer in the future. Furthermore, international comparison studies using well-designed and uniform methodology to clarify the risk in specific sexes, ethnicities, and other subgroups and to evaluate the interaction with other environmental risk factors or medications will be helpful to identify patients at risk.