New-onset diabetes with a history of dyslipidemia predicts pancreatic cancer

Mechanisms of obesity- and diabetes mellitus-related pancreatic carcinogenesis: a comprehensive and systematic review

Research on obesity- and diabetes mellitus (DM)-related carcinogenesis has expanded exponentially since these two diseases were recognized as important risk factors for cancers. The growing interest in this area is prominently actuated by the increasing obesity and DM prevalence, which is partially responsible for the slight but constant increase in pancreatic cancer (PC) occurrence. PC is a highly lethal malignancy characterized by its insidious symptoms, delayed diagnosis, and devastating prognosis. The intricate process of obesity and DM promoting pancreatic carcinogenesis involves their local impact on the pancreas and concurrent whole-body systemic changes that are suitable for cancer initiation. The main mechanisms involved in this process include the excessive accumulation of various nutrients and metabolites promoting carcinogenesis directly while also aggravating mutagenic and carcinogenic metabolic disorders by affecting multiple pathways. Detrimental alterations in gastrointestinal and sex hormone levels and microbiome dysfunction further compromise immunometabolic regulation and contribute to the establishment of an immunosuppressive tumor microenvironment (TME) for carcinogenesis, which can be exacerbated by several crucial pathophysiological processes and TME components, such as autophagy, endoplasmic reticulum stress, oxidative stress, epithelial-mesenchymal transition, and exosome secretion. This review provides a comprehensive and critical analysis of the immunometabolic mechanisms of obesity- and DM-related pancreatic carcinogenesis and dissects how metabolic disorders impair anticancer immunity and influence pathophysiological processes to favor cancer initiation.

Risk Factors for Pancreatic Cancer in Patients with New-Onset Diabetes: A Systematic Review and Meta-Analysis

(1) Background: Patients with new-onset diabetes (NOD) are at risk of pancreatic ductal adenocarcinoma (PDAC), but the most relevant additional risk factors and clinical characteristics are not well established. (2) Objectives: To compare the risk for PDAC in NOD patients to persons without diabetes. Identify risk factors of PDAC among NOD patients. (3) Methods: Medline, Embase, and Google Scholar were last searched in June 2022 for observational studies on NOD patients and assessing risk factors for developing PDAC. Data were extracted, and Meta-Analysis was performed. Pooled effect sizes with 95% confidence intervals (CI) were estimated with DerSimonian & Laird random effects models. (4) Findings: Twenty-two studies were included, and 576,210 patients with NOD contributed to the analysis, of which 3560 had PDAC. PDAC cases were older than controls by 6.14 years (CI 3.64–8.65, 11 studies). The highest risk of PDAC involved a family history of PDAC (3.78, CI 2.03–7.05, 4 studies), pancreatitis (5.66, CI 2.75–11.66, 9 studies), cholecystitis (2.5, CI 1.4–4.45, 4 studies), weight loss (2.49, CI 1.47–4.22, 4 studies), and high/rapidly increasing glycemia (2.33, CI 1.85–2.95, 4 studies) leading to more insulin use (4.91, CI 1.62–14.86, 5 studies). Smoking (ES 1.20, CI 1.03–1.41, 9 studies) and alcohol (ES 1.23, CI 1.09–1.38, 9 studies) have a smaller effect. (5) Conclusion: Important risk factors for PDAC among NOD patients are age, family history, and gallstones/pancreatitis. Symptoms are weight loss and rapid increase in glycemia. The identified risk factors could be used to develop a diagnostic model to screen NOD patients.

Risk Factors for Pancreatic Cancer in Patients with New-Onset Diabetes: A Systematic Review and Meta-Analysis

(1) Background: Patients with new-onset diabetes (NOD) are at risk of pancreatic ductal adenocarcinoma (PDAC), but the most relevant additional risk factors and clinical characteristics are not well established. (2) Objectives: To compare the risk for PDAC in NOD patients to persons without diabetes. Identify risk factors of PDAC among NOD patients. (3) Methods: Medline, Embase, and Google Scholar were last searched in June 2022 for observational studies on NOD patients and assessing risk factors for developing PDAC. Data were extracted, and Meta-Analysis was performed. Pooled effect sizes with 95% confidence intervals (CI) were estimated with DerSimonian & Laird random effects models. (4) Findings: Twenty-two studies were included, and 576,210 patients with NOD contributed to the analysis, of which 3560 had PDAC. PDAC cases were older than controls by 6.14 years (CI 3.64–8.65, 11 studies). The highest risk of PDAC involved a family history of PDAC (3.78, CI 2.03–7.05, 4 studies), pancreatitis (5.66, CI 2.75–11.66, 9 studies), cholecystitis (2.5, CI 1.4–4.45, 4 studies), weight loss (2.49, CI 1.47–4.22, 4 studies), and high/rapidly increasing glycemia (2.33, CI 1.85–2.95, 4 studies) leading to more insulin use (4.91, CI 1.62–14.86, 5 studies). Smoking (ES 1.20, CI 1.03–1.41, 9 studies) and alcohol (ES 1.23, CI 1.09–1.38, 9 studies) have a smaller effect. (5) Conclusion: Important risk factors for PDAC among NOD patients are age, family history, and gallstones/pancreatitis. Symptoms are weight loss and rapid increase in glycemia. The identified risk factors could be used to develop a diagnostic model to screen NOD patients.

Reduced Incidence of Stroke in Patients with Gout Using Benzbromarone

Gout is strongly associated with the incidence of atherosclerotic events, including stroke and myocardial infarction. Considering the increased prevalence of stroke in the population with gout, the aim of this study was to evaluate the effects of benzbromarone, a uricosuric agent, on the incidence of stroke in the population with gout. We used data from the Taiwanese National Health Insurance Registration Database (NHIRD). The benzbromarone user cohort included 15,143 patients; each patient was age- and sex-matched with one non-user randomly selected from the population with gout. Cox proportional hazard regression analysis was conducted to estimate the effects of benzbromarone on the incidence of stroke in the population with gout. The incidence of stroke was significantly lower in benzbromarone users than in benzbromarone non-users. The HR for the incidence of stroke was lower in male benzbromarone users than in non-users. An analysis of three age groups (<40, 40–59, and ≥60 years) indicated that the HRs in those aged 40–59 years and ≥60 years were significantly lower among benzbromarone users than non-users. In the population with gout, the incidence of stroke was lower in benzbromarone users than in benzbromarone non-users.

Diabetes and pancreatic cancer: Exploring the two-way traffic

Pancreatic cancer (PC) is often associated with a poor prognosis. Long-standing diabetes mellitus is considered as an important risk factor for its development. This risk can be modified by the use of certain antidiabetic medications. On the other hand, new-onset diabetes can signal towards an underlying PC in the elderly population. Recently, several attempts have been made to develop an effective clinical tool for PC screening using a combination of history of new-onset diabetes and several other clinical and biochemical markers. On the contrary, diabetes affects the survival after treatment for PC. We describe this intimate and complex two-way relationship of diabetes and PC in this review by exploring the underlying pathogenesis.

Mendelian randomisation study of the effects of known and putative risk factors on pancreatic cancer

BACKGROUND

Observational studies have reported multiple risk factors for pancreatic ductal adenocarcinoma (PDAC). Some are well established, like tobacco smoking, alcohol drinking, obesity and type 2 diabetes, whereas some others are putative, such as allergy and dietary factors. Identifying causal risk factors can help establishing those that can be targeted to contribute to prevent PDAC.

OBJECTIVE

We sought to investigate the possible causal effects of established and putative factors on PDAC risk.

METHODS

We conducted a two-sample Mendelian randomisation (MR) study using publicly available data for genetic variants associated with the factors of interest, and summary genetic data from genome-wide association studies of the Pancreatic Cancer Cohort Consortium (PanScan) and the Pancreatic Cancer Case-Control Consortium (PanC4), including in total 8769 cases and 7055 controls. Causality was assessed using inverse-variance weighted, MR-Egger regression and weighted median methods, complemented with sensitivity and radial MR analyses.

RESULTS

We found evidence for a causal effect of body mass index (BMI) on PDAC risk (OR 1.43, 95% CI 1.20 to 1.71, p=8.43×10^-5). Fasting insulin (OR 2.84, 95% CI 1.23 to 6.56, p=0.01), low-density lipoprotein cholesterol (OR 1.16, 95% CI 1.02 to 1.32, p=0.03) and type 2 diabetes (OR 1.09, 95% CI 1.01 to 1.17, p=0.02) were also causally associated with PDAC risk. BMI showed both direct and fasting insulin-mediated causal effects.

CONCLUSION

We found strong evidence that BMI is causally associated with PDAC risk, providing support that obesity management may be a potential prevention strategy for reducing pancreatic cancer risk while fasting insulin and type 2 diabetes showed a suggestive association that should be further investigated.

Development of a prediction model for pancreatic cancer in patients with type 2 diabetes using logistic regression and artificial neural network models

Objectives

Patients with type 2 diabetes (T2DM) are suggested to have a higher risk of developing pancreatic cancer. We used two models to predict pancreatic cancer risk among patients with T2DM.

Methods

The original data used for this investigation were retrieved from the National Health Insurance Research Database of Taiwan. The prediction models included the available possible risk factors for pancreatic cancer. The data were split into training and test sets: 97.5% of the data were used as the training set and 2.5% of the data were used as the test set. Logistic regression (LR) and artificial neural network (ANN) models were implemented using Python (Version 3.7.0). The F₁, precision, and recall were compared between the LR and the ANN models. The areas under the receiver operating characteristic (ROC) curves of the prediction models were also compared.

Results

The metrics used in this study indicated that the LR model more accurately predicted pancreatic cancer than the ANN model. For the LR model, the area under the ROC curve in the prediction of pancreatic cancer was 0.727, indicating a good fit.

Conclusion

Using this LR model, our results suggested that we could appropriately predict pancreatic cancer risk in patients with T2DM in Taiwan.

Decreased incidence of diabetes in patients with gout using benzbromarone

Objective

Insulin resistance is inversely correlated with the clearance rate of uric acid, which may indicate that improvement in the clearance rate of uric acid could reduce insulin resistance. Considering the increased prevalence of diabetes mellitus (DM) in the gout population, this study evaluated the effects of benzbromarone, a uricosuric agent, on the incidence of DM in the gout population.

Methods

We used data from the Taiwan National Health Insurance program. The benzbromarone user cohort included 8678 patients; each patient was age- and sex-matched with one benzbromarone non-user who was randomly selected from the gout population. The Cox proportional hazard regression analysis was conducted to estimate the effects of benzbromarone on the incidence of DM in the gout population.

Results

The incidence of DM was significantly lower in benzbromarone users than in benzbromarone non-users [adjusted hazard ratio (HR) = 0.86; 95% CI: 0.79, 0.94]. The HR for the incidence of DM was lower in male benzbromarone users (adjusted HR = 0.77; 95% CI: 0.69, 0.86) than in benzbromarone non-users. An analysis of three age groups (<40, 40-59 and ⩾60 years) indicated that the HRs of the age groups of 40-59 years (adjusted HR = 0.86; 95% CI: 0.76, 0.98) and ⩾60 years (adjusted HR = 0.82; 95% CI: 0.71, 0.94) were significantly lower among benzbromarone users than among benzbromarone non-users.

Conclusion

In the gout population, the incidence of DM was lower in benzbromarone users than in benzbromarone non-users.

Type 2 diabetes mellitus is more prevalent among patients with thyroid carcinoma and influences overall survival: a propensity score matching analysis

The relationship between Type 2 Diabetes Mellitus(T2DM) and cancer risk has been investigated for more than a decade. Many types of cancer were confirmed to be related with T2DM. The aim of this study is to identify the relationship between T2DM and the prevalence and long-term survivals of Thyroid Carcinoma(TC) using propensity score matching. In present study, 1658 thyroid nodule patients who were diagnosis in Beijing Shijitan hospital were divided into two groups: the TC group (N = 455, 27.4%), and the benign thyroid nodule(BTN) group (N = 1203, 73.6%). Propensity scores analyses were used to compare the overall survival (OS) and recurrence-free survival (RFS) between patients with or without T2DM. After propensity scores analyses, the prevalance of T2DM was significantly increased in the TC group compared with BTN group. Of the 455 TC patients, with T2DM in thyroid carcinoma was associated with increasing 1-, 3-, 5-year OS rates from 98.8, 76.5, and 70.9% to 99.7, 92.2, and 82.7%, respectively (P=0.017). While the 1-, 3-, and 5-year RFS rates in the group with T2DM were 92.3, 69.5, and 58.3%, which were significantly lower than those in the group without T2DM (97.6, 82.7, and 72.4%, P=0.009). After propensity scores analyses, with T2DM was significantly associated with increased risks of OS and RFS in the entire TC cohort.

Type 2 diabetes mellitus is associated with increased risk of pancreatic cancer: A veteran administration registry study

BACKGROUND

The etiology of pancreatic cancer remains elusive. Several studies have suggested a role for diabetes mellitus, but the magnitude of its contribution remains controversial.

OBJECTIVES

Utilizing a large administrative database, this retrospective cohort study was designed to investigate the relationship between type 2 diabetes mellitus and pancreatic cancer.

PATIENTS AND DESIGN

Using the Veterans Integrated Services Network 16 database, 322,614 subjects were enrolled in the study, including 110,919 with type 2 diabetes mellitus and 211,695 diabetes-free controls matched by gender, year of birth and healthcare facility.

RESULTS

A significantly higher incidence of pancreatic cancer was observed in patients with type 2 diabetes mellitus, with an adjusted hazard ratio (95% confidence interval) of 2.17 (1.70-2.77) for type 2 diabetes mellitus compared to controls (p < 10^-9) after controlling for the matching factors.

CONCLUSION

The association between type 2 diabetes mellitus and pancreatic cancer was statistically significant and may, in part, explain the rising incidence of pancreatic cancer.

Sitagliptin and pancreatic cancer risk in patients with type 2 diabetes

BACKGROUND

The risk of pancreatic cancer associated with incretin-based therapies is controversial.

METHODS

This study retrospectively analysed the National Health Insurance database including patients with newly diagnosed type 2 diabetes mellitus at an age ≥ 25 years between 1999 and 2010. A total of 71 137 ever users of sitagliptin and 933 046 never users were followed for pancreatic cancer until 31 December 2011. A time-dependent approach was used to calculate incidence and estimate hazard ratios adjusted for propensity score using Cox regression.

RESULTS

During follow-up, 83 ever users and 3658 never users developed pancreatic cancer, representing an incidence of 73·6 and 55·0 per 100 000 person-years, respectively. The adjusted hazard ratio (95% confidence intervals) for ever versus never users was 1·40 (1·13-1·75). The respective adjusted hazard ratio for the first, second and third tertile of cumulative dose < 14 700, 14 700-33 700 and > 33 700 mg was 1·83 (1·28-2·62), 1·97 (1·41-2·76) and 0·72 (0·45-1·15). For average daily dose of < 50, 50-99·9 and ≥ 100 mg, the respective hazard ratio was 3·10 (1·17-8·26), 1·01 (0·63-1·61) and 1·53 (1·18-1·97).

CONCLUSIONS

Sitagliptin is significantly associated with a higher risk of pancreatic cancer, especially when the cumulative dose is < 33 700 mg. The risk diminished in users with a higher cumulative dose. The daily dose of sitagliptin should better be kept < 100 mg, and its use should be reconsidered in patients who suffer from severe renal impairment and thus a daily dose of < 50 mg is always recommended. Future studies are required to confirm the findings with more appropriate adjustment for smoking.

Rosiglitazone may reduce non-melanoma skin cancer risk in Taiwanese

Background

Whether rosiglitazone may affect the risk of non-melanoma skin cancer (NMSC) has not been investigated.

Methods

The reimbursement databases of all Taiwanese diabetic patients from 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at 1 January 2006 and a total of 886418 patients with type 2 diabetes were followed up for NMSC incidence until the end of 2009. Incidences for ever-users, never-users and subgroups of rosiglitazone exposure (using tertile cutoffs of duration of therapy and cumulative dose) were calculated and hazard ratios estimated by Cox regression. Additional models were created as sensitivity analyses.

Results

There were 103097 ever-users and 783321 never-users, respective numbers of incident NMSC 250 (0.24%) and 2084 (0.27%), and respective incidence 68.90 and 76.77 per 100000 person-years. Although the overall hazard ratio was not significant in the unadjusted, age-sex-adjusted or fully adjusted model, the risk was significantly lower in the third tertile of duration of therapy and cumulative dose, with significant P for trends. The fully adjusted hazard ratio (95% confidence interval) for a duration of therapy >13.77 months and a cumulative dose of >1752 mg was 0.723 (0.566, 0.923) and 0.783 (0.618, 0.993), respectively. The findings were supported by various sensitivity analyses.

Conclusions

Rosiglitazone may reduce the risk of NMSC, but further confirmation is required.

An updated review on cancer risk associated with incretin mimetics and enhancers

Incretin-based therapies, including the use of incretin mimetics of glucagon-like peptide-1 receptor (GLP-1R) agonists and incretin enhancers of dipeptidyl-peptidase 4 (DPP-4) inhibitors, are widely used by clinicians for glucose lowering in patients with type 2 diabetes mellitus. These agents have benefits of a lower risk of hypoglycemia, being neutral for body weight for DPP-4 inhibitors and having a potential for weight reduction with GLP-1R agonists. They may also have a neutral or beneficial cardiovascular effect. Despite these benefits, an increased risk of cancer (especially pancreatic cancer and thyroid cancer) associated with incretin-based therapies has been reported. In this article, we reviewed related literature of experimental animal and observational human studies, clinical trials, and meta-analyses published until December 15, 2014. Current studies suggested a probable role of GLP-1R activation on the development of pancreatic cancer and thyroid cancer in rodents, but such an effect in humans is not remarkable due to the lower or lack of expression of GLP-1R on human pancreatic ductal cells and thyroid tissues. Findings in human studies are controversial and inconclusive. In the analyses of the US Food and Drug Administration adverse events reporting system, a significantly higher risk of pancreatic cancer was observed for GLP-1R agonists and DPP-4 inhibitors, but a significantly higher risk of thyroid cancer was only observed for GLP-1R agonists. Such a higher risk of pancreatic cancer or thyroid cancer could not be similarly demonstrated in other human observational studies or analyses of data from clinical trials. With regards to cancers other than pancreatic cancer and thyroid cancer, available studies supported a neutral association in humans. Some preliminary studies even suggested a potentially beneficial effect on the development of other cancers with the use of incretins. Based on current evidence, continuous monitoring of the cancer issues related to incretin-based therapies is required, even though the benefits may outweigh the potential cancer risk in the general patients with type 2 diabetes mellitus.

Metformin reduces thyroid cancer risk in Taiwanese patients with type 2 diabetes

Background

Whether metformin may affect thyroid cancer risk has not been studied. This study investigated the association between metformin use and thyroid cancer risk in Taiwanese patients with type 2 diabetes mellitus.

Methods

The reimbursement databases of all diabetic patients from 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at 1 January 2006 and 1,414,723 patients with type 2 diabetes were followed for thyroid cancer incidence until the end of 2009. Incidences for ever-users, never-users and subgroups of metformin exposure using tertile cutoffs for cumulative duration of therapy and cumulative dose were calculated and adjusted hazard ratios were estimated by Cox regression. Additional sensitivity analyses were conducted.

Results

There were 795,321 ever-users and 619,402 never-users, with respective numbers of incident thyroid cancer of 683 (0.09%) and 1,614 (0.26%), and respective incidence of 24.09 and 87.33 per 100,000 person-years. The overall fully adjusted hazard ratio (95% confidence interval) was 0.683 (0.598–0.780), and all categories of the dose-response parameters showed significantly lower risk with P-trends <0.0001. The protective effect of metformin on thyroid cancer incidence was also supported by sensitivity analyses, disregarding age (<50 or ≥50 years) and sex; and was not affected by excluding users of insulin, sulfonylurea, and insulin and/or sulfonylurea respectively, by previous diagnosis of other cancers or by potential detection examinations that might lead to differential diagnosis of thyroid cancer.

Conclusions

This study provides evidence for the first time that metformin use in patients with type 2 diabetes may reduce the risk of thyroid cancer.

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.

Metformin may reduce breast cancer risk in Taiwanese women with type 2 diabetes

Whether metformin therapy affects breast cancer risk in Asian patients with type 2 diabetes mellitus (T2DM) has not been investigated. The reimbursement databases of Taiwanese female patients with a new diagnosis of T2DM between 1998 and 2002 (n = 476,282) were retrieved from the National Health Insurance for follow-up of breast cancer until the end of 2009. Metformin was treated as a time-dependent variable; and of these patients, 285,087 were never-users and 191,195 were ever-users. A time-dependent approach was used to calculate breast cancer incidence and estimate hazard ratios by Cox regression for ever-users, never-users, and subgroups of metformin exposure (tertiles of cumulative duration and cumulative dose). During follow-up, 2,412 (1.26 %) metformin ever-users and 9,322 (2.10 %) never-users developed breast cancer, representing an incidence of 201.08 and 535.88 per 100,000 person-years, respectively. The overall multivariable-adjusted hazard ratio (95 % confidence intervals) for ever- versus never-users was 0.630 (0.597-0.665). The multivariable-adjusted hazard ratios for the first, second, and third tertiles of cumulative duration of metformin therapy were 1.122 (1.043-1.207), 0.754 (0.692-0.820), and 0.280 (0.253-0.310), respectively, (P-trend <0.0001); and 1.099 (1.021-1.182), 0.664 (0.611-0.723), and 0.311 (0.281-0.344), respectively, (P-trend <0.0001), for cumulative dose of metformin. Metformin use is associated with a decreased risk of breast cancer.

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.

Human insulin does not increase bladder cancer risk

Background

Whether human insulin can induce bladder cancer is rarely studied.

Methods

The reimbursement databases of all Taiwanese diabetic patients from 1996 to 2009 were retrieved from the National Health Insurance. An entry date was set at 1 January 2004 and a total of 785,234 patients with type 2 diabetes were followed up for bladder cancer incidence until the end of 2009. Users of pioglitazone were excluded and the period since the initiation of insulin glargine (marketed after the entry date in Taiwan) was not included in the calculation of follow-up. Incidences for ever-users, never-users and subgroups of human insulin exposure (using tertile cutoffs of time since starting insulin, duration of therapy and cumulative dose) were calculated and the hazard ratios were estimated by Cox regression.

Results

There were 87,940 ever-users and 697,294 never-users, with respective numbers of incident bladder cancer of 454 (0.52%) and 3,330 (0.48%), and respective incidence of 120.49 and 94.74 per 100,000 person-years. The overall hazard ratios (95% confidence intervals) indicated a significant association with insulin in the age-sex-adjusted models [1.238 (1.122–1.366)], but not in the model adjusted for all covariates [1.063 (0.951–1.187)]. There was also a significant trend for the hazard ratios for the different categories of the dose-response parameters in the age-sex-adjusted models, which became insignificant when all covariates were adjusted.

Conclusions

This study relieves the concern of a bladder cancer risk associated with human insulin. Appropriate adjustment for confounders is important in the evaluation of cancer risk associated with a medication.

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.

Rosiglitazone may reduce thyroid cancer risk in patients with type 2 diabetes

BACKGROUND

Whether rosiglitazone use in patients with type 2 diabetes may affect thyroid cancer risk has not been investigated.

METHODS

The reimbursement databases of all diabetic patients under oral anti-diabetic agents or insulin from 1996 to 2009 were retrieved from the National Health Insurance of Taiwan. An entry date was set at 1 January 2006, and 887,665 patients with type 2 diabetes were followed for thyroid cancer incidence until the end of 2009 for ever-users, never-users, and subgroups of rosiglitazone exposure using tertile cut-offs for time since starting rosiglitazone, duration of therapy, and cumulative dose. Hazard ratios were estimated by Cox regression.

RESULTS

There were 103,224 ever-users and 784,441 never-users, with respective numbers of incident thyroid cancer of 84 (0.08%) and 764 (0.10%), and respective incidence of 23.12 and 28.09 per 100,000 person-years. The overall multivariable-adjusted hazard ratio was not significant. However, in dose-response analyses, the adjusted hazard ratios (95% confidence intervals) were significant for the third tertile of duration of therapy (≥ 14 months) and cumulative dose (≥ 1,800 mg) for age ≥ 50 years: 0.53 (0.31-0.89) and 0.50 (0.29-0.87), respectively.

CONCLUSIONS

This study suggests that rosiglitazone use in patients with type 2 diabetes may reduce the risk of thyroid cancer.

Pioglitazone and oral cancer risk in patients with type 2 diabetes

BACKGROUND

Pioglitazone has shown an inhibitory effect on the growth of cell lines derived from human salivary gland and human oral squamous cell carcinoma. However, whether this effect can be applied to patients with type 2 diabetes mellitus who use pioglitazone for glycemic control remains unanswered.

METHODS

The reimbursement records of all Taiwanese diabetic patients under treatment with oral anti-diabetic agents or insulin from 1996 to 2009 were retrieved from the National Health Insurance database. The entry date was set at 1 January 2006 and a total of 1,093,391 patients with type 2 diabetes were followed up for oral cancer incidence till the end of 2009. Incidences for ever-users, never-users and subgroups of pioglitazone dose-responsive exposure (using the parameters of time since starting pioglitazone, duration of therapy and cumulative dose) were calculated and hazard ratios estimated by Cox regression.

RESULTS

There were 58,238 ever-users and 1,035,153 never-users, with respective numbers of incident oral cancer of 201 (0.35%) and 4168 (0.40%), and respective incidences of 94.26 and 114.24 per 100,000 person-years. The overall hazard ratios (95% confidence intervals) did show a significantly lower risk in unadjusted [0.832 (0.722-0.958)] and age-sex-adjusted [0.866 (0.752-0.998)] models. However, the multivariable-adjusted hazard ratio (95% confidence interval) was not significant: 0.992 (0.857-1.148). Although significant P-trends for the dose-response parameters could be observed in some of the unadjusted and age-sex-adjusted models, none was significant in the multivariable-adjusted models.

CONCLUSIONS

Pioglitazone has a null association with oral cancer after adjustment for potential confounders.

The bidirectional interation between pancreatic cancer and diabetes

The bidirectional interation between pancreatic cancer (PanCa) and diabetes has been confirmed by epidemiological studies, which provide evidence-based medical support for further research into the mechanisms involved in the interaction. We reviewed the literature regarding the role of diabetes in the generation and progression of PanCa and the mechanism by which PanCa induces diabetes for its malignant progression. The effect of antidiabetic drugs on the occurrence and prognosis of PanCa was also reviewed. Diabetes may directly promote the progression of PanCa by pancreatic duct enlargement and hypertension, as well as by enabling an increased tumor volume. Hyperinsulinemia, insulin resistance, cytokines, hyperglycemia and genotype change are also important factors in the progression of PanCa with diabetes. Hyperglycemia may be the first clinical manifestation and is helpful in the early diagnosis of PanCa. Furthermore, antidiabetic drugs can have different effects on the occurrence and prognosis of PanCa. The bidirectional interation between PanCa and diabetes is involved in the occurrence, proliferation, invasion, metastasis and prognosis of PanCa with diabetes. The discovery of biomarkers for the early diagnosis of PanCa, as well as the novel usage of metformin for its antitumor effects and determining the potential mechanisms of these effects, may be the next direction for PanCa research and treatment.