Diabetes and cancer

Modest increase in risk of specific types of cancer types in type 2 diabetes mellitus patients

Most studies associated diabetes mellitus (DM) with risk of cancer have focused on the Caucasian population and only a few types of cancer. Therefore, a large and comprehensive nationwide retrospective cohort study involving an Asian population was conducted to evaluate the risk of several major types of cancer among Type 2 DM patients. The study analyzed the nationwide population-based database from 1996 to 2009 released by the National Health Research Institute in Taiwan. Incidence and hazard ratios (HRs) were calculated for specific types of cancer. The overall risk of cancers was significantly greater in the DM cohort [N = 895,434; HR = 1.19, 95% confidence interval (CI) = 1.17-1.20], compared with non-DM controls (N = 895,434). Several organs in the digestive and urogenital systems showed increased risk of cancer. The three highest HRs were obtained from cancers of the liver (HR = 1.78, 95% CI = 1.73-1.84), pancreatic (HR = 1.52, 95% CI = 1.40-1.65), and uterus and corpus (HR = 1.38, 95% CI = 1.22-1.55). The risk increased with age, and men with DM aged ≥ 75 years exhibited the highest risk (HR = 7.76, 95% CI = 7.39-8.15). Subjects with DM in this population have a modest increased risk of cancer, similar to the Caucasian population for several specific types of cancer. Old men with DM have the highest risk of cancer. Careful screening for cancer in DM patients is important for early diagnosis and effective treatment.

From tumor cell metabolism to tumor immune escape

Tumorigenesis implies adaptation of tumor cells to an adverse environment. First, developing tumors must acquire nutrients to ensure their rapid growth. Second, they must escape the attack from the host immune system. Recent studies suggest that these phenomena could be related and that tumor cell metabolism may propel tumor immune escape. Tumor cell metabolism tends to avoid mitochondrial activity and oxidative phosphorylation (OXPHOS), and largely relies on glycolysis to produce energy. This specific metabolism helps tumor cells to avoid the immune attack from the host by blocking or avoiding the immune attack. By changing their metabolism, tumor cells produce or sequester a variety of amino acids, lipids and chemical compounds that directly alter immune function therefore promoting immune evasion. A second group of metabolism-related modification targets the major histocompatibility complex-I (MHC-I) and related molecules. Tumor MHC-I presents tumor-associated antigens (TAAs) to cytotoxic T-cells (CTLs) and hence, sensitizes cancer cells to the cytolytic actions of the anti-tumor adaptive immune response. Blocking tumor mitochondrial activity decreases expression of MHC-I molecules at the tumor cell surface. And peroxynitrite (PNT), produced by tumor-infiltrating myeloid cells, chemically modifies MHC-I avoiding TAA expression in the plasma membrane. These evidences on the role of tumor cell metabolism on tumor immune escape open the possibility of combining drugs designed to control tumor cell metabolism with new procedures of anti-tumor immunotherapy. This article is part of a Directed Issue entitled: Bioenergetic dysfunction, adaptation and therapy.

Diabetes and cancer I: risk, survival, and implications for screening

Type 2 diabetes mellitus (DM) and cancer are common diseases that are frequently diagnosed in the same individual. An association between the two conditions has long been postulated. Here, we review the epidemiological evidence for increased risk of cancer, decreased cancer survival, and decreased rates of cancer screening in diabetic patients. The risk for several cancers, including cancers of the pancreas, liver, colorectum, breast, urinary tract, and endometrium, is increased in patients with DM. In a pooled risk analysis weighting published meta-analytic relative risk (RR) for individual cancer by differences in their incidence rates, we found a population RR of 0.97 (95 % CI, 0.75-1.25) in men and 1.29 (95 % CI, 1.16-1.44) in women. All meta-analyses showed an increased relative risk for cancer in diabetic men, except studies of prostate cancer, in which a protective effect was observed. The relationship between diabetes and cancer appears to be complex, and at present, a clear temporal relationship between the two conditions cannot be defined. DM also impacts negatively on cancer-related survival outcomes and cancer screening rates. The overwhelming evidence for lower cancer screening rates, increased incidence of certain cancers, and poorer prognosis after cancer diagnosis in diabetic patients dictates a need for improved cancer care in diabetic individuals through improved screening measures, development of risk assessment tools, and consideration of cancer prevention strategies in diabetic patients. Part two of this review focuses on the biological and pharmacological mechanisms that may account for the association between DM and cancer.

Risk of asthma and autoimmune diseases and related conditions in patients hospitalized for obesity

BACKGROUND

Although there are putative mechanistic links between obesity and autoimmune diseases, obesity is not considered a risk factor for most autoimmune diseases.

METHODS

Using the nation-wide Hospital Discharge Register we defined a cohort of 29,665 patients hospitalized for obesity since year 1964. The patients were followed for hospitalization for any of 34 autoimmune or related conditions through year 2007. Standardized incidence ratios (SIRs) were calculated for autoimmune diseases in obese individuals compared to those who had not been hospitalized for obesity.

RESULTS

Among 22 immune diseases diagnosed after hospitalization for obesity and in at least 5 patients, the overall SIR was 2.05. Of the individual diseases studied, the risk of 16 was significantly increased; none displayed a decreased risk. Psoriasis (4.54) and Behçet's disease (4.49) exhibited the highest risks, followed by Hashimoto's disease/hypothyroidism (4.12) and asthma (3.39). Small but significant increases in SIRs were also noted for the common autoimmune diseases Graves's disease/hyperthyroidism (1.28) and rheumatoid arthritis (1.37).

CONCLUSIONS

The present population of obese individuals, subsequently diagnosed with a number of autoimmune diseases and related conditions, was hospitalized at a relatively young age. Further studies are needed to describe the morbidity in the obese population at large.

Association of thiazolidinediones with liver cancer and colorectal cancer in type 2 diabetes mellitus

The objective of this nationwide case-control study was to evaluate the risk of specific malignancy in diabetic patients who received thiazolidinediones (TZDs). A total of 606,583 type 2 diabetic patients, age 30 years and above, without a history of cancer were identified from the Taiwan National Health Insurance claims database during the period between January 1 2000 and December 31 2000. As of December 31 2007, patients with incident cancer of liver, colorectal, lung, and urinary bladder were included as cases and up to four age- and sex-matched controls were selected by risk-set sampling. Logistic regression models were applied to estimate the odds ratio (OR) and 95% confidence interval (CI) between TZDs and cancer incidence. A total of 10,741 liver cancer cases, 7,200 colorectal cancer cases, and 70,559 diabetic controls were included. A significantly lower risk of liver cancer incidence was found for any use of rosiglitazone (OR: 0.73, 95% CI: 0.65-0.81) or pioglitazone (OR: 0.83, 95% CI: 0.72-0.95), respectively. The protective effects were stronger for higher cumulative dosage and longer duration. For colorectal cancer, rosiglitazone, but not pioglitazone, was associated with a significantly reduced risk (OR: 0.86; 95% CI: 0.76-0.96). TZDs were not associated with lung and bladder cancer incidence, although a potential increased risk for bladder cancer with pioglitazone use ≥3 years could not be excluded (OR: 1.56; 95% CI: 0.51-4.74).

CONCLUSION

The use of pioglitazone and rosiglitazone is associated with a decreased liver cancer incidence in diabetic patients. The effects on occurrence of specific cancer types may be different for pioglitazone and rosiglitazone.

Proinsulin binds with high affinity the insulin receptor isoform A and predominantly activates the mitogenic pathway

Proinsulin is generally regarded as an inactive prohormone because of its low metabolic activity. However, proinsulin appears to regulate embryo development in animal models. In this study, we evaluated whether proinsulin may differentially bind to and activate the two insulin receptor (IR) isoforms (IR-A and IR-B), because IR-A is a relatively low-specificity receptor that is prevalent in fetal and cancer cells and is able to mediate the growth effects of IGF-II. Mouse R(-) fibroblasts devoid of IGF-I receptor (IGF-IR) and stably transfected with cDNA encoding either human IR-A or IR-B (R(-) /IR-A and R(-) /IR-B cells) were used. Three human cancer cell lines were also studied. We found that proinsulin stimulated phosphorylation of IR-A with an EC(50) of 4.5 ± 0.6 nm and displaced [(125)I]insulin from IR-A with a similar EC(50). In contrast, proinsulin EC(50) values for stimulation of IR-B phosphorylation and for [(125)I]insulin displacement from IR-B were approximately 7-fold higher. Proinsulin did not bind or activate IGF-IR or IR/IGF-IR hybrids. Via IR-A, proinsulin activated the ERK/p70S6K pathway to a similar degree as insulin but elicited a weaker Akt response. Despite its low metabolic activity, proinsulin was almost equipotent as insulin in inducing cell proliferation and migration in cells expressing various IR-A levels. In conclusion, proinsulin is a selective IR-A ligand and may induce biological effects through this IR isoform.

Survival advantage observed with the use of metformin in patients with type II diabetes and colorectal cancer

BACKGROUND

Patients with type II diabetes mellitus (DM) have an increased risk of adenomatous colorectal (CRC) polyps and CRC cancer. The use of the anti-hyperglycemic agent metformin is associated with a reduced incidence of cancer-related deaths.

METHODS

We retrospectively evaluated the medical records of 4758 patients seen at a single institution and determined that 424 patients were identified by their physicians as having type II DM and CRC cancer. Data were subsequently acquired determining the subject's age, body mass index (BMI), and disease date of diagnosis, stage, site of cancer, treatment, and survival.

RESULTS

Patients with type II DM and CRC cancer treated with metformin as one of their diabetic medications had a survival of 76.9 months (95% CI=61.4-102.4) as compared with 56.9 months in those patients not treated with metformin (95% CI=44.8-68.8), P=0.048. By using a multivariable Cox regression model adjusted for age, sex, race, BMI, and initial stage of disease, we demonstrated that type II diabetic patients treated with metformin had a 30% improvement in overall survival (OS) when compared with diabetic patients treated with other diabetic agents.

CONCLUSION

Colorectal cancer patients with DM treated with metformin as part of their diabetic therapy appear to have a superior OS.

A metabolic phenotyping approach to understanding relationships between metabolic syndrome and breast tumour responses to chemotherapy

PURPOSE

Breast cancer is associated with adverse outcomes in patients with the metabolic syndrome phenotype. To study this further, we examined the relationship between serum metabolite levels and the components of metabolic syndrome with treatment outcomes in breast cancer.

METHODS

A total of 88 women with measurable breast cancer were studied; their serum metabolites as assessed by (1)H nuclear magnetic resonance spectroscopy, blood pressure, lipids, glucose, body mass index and waist circumference were recorded and correlated with treatment response.

RESULTS

We identified metabolic syndrome in approximately half of our cohort (42 patients) and observed a significant trend (P = 0.03) of increased incidence of metabolic syndrome in partial response (33.3%), stable disease (42.9%) and progressive disease groups (66.1%). High blood sugar predicted a poor response (P < 0.001). Logistic regression of metabonomic data demonstrated that high lactate (P = 0.03) and low alanine (P = 0.01) combined with high glucose (P = 0.01) were associated with disease progression.

CONCLUSIONS

Metabolic syndrome is commonly observed in metastatic breast cancer and these patients have poorer outcomes. These data, which support our previous findings, suggest that high blood glucose as part of metabolic syndrome is associated with a poor response in breast cancer. They also validate new therapeutic approaches that focus on metabolism.

[Advances in the prevention, diagnosis and therapy of vascular diseases]

Atherosclerosis is a systemic disease affecting the coronary, carotid, intracerebral, renal and peripherial arteries. The early morphological and functional impairments could be detected in the second or third decades of life and their progression depend on the number and severity of risk factors and individual susceptility. Although the vascular risk factors (smoking, overweight, age, unhealthy diet, lack of physical exercise, hypertension, diabetes mellitus, chronic kidney disease and dyslipidemia) are the same and common in the different vascular diseases, the present clinical routine artificially classifies the diagnosis and therapy of different vascular diseases into different subfields of medicine with the negative impact of possible polypragmasia. Recently, worldwide health surveys (e.g. REACH registry) have proven the usefulness of a holistic approach in the diagnosis and therapy of multiorgan-affected vascular patients. This review summarizes the multidisciplinary advances and future perspective of vascular diseases.

Glucose-lowering agents and the patterns of risk for cancer: a study with the General Practice Research Database and secondary care data

INTRODUCTION

Recent studies suggesting an increased cancer risk with glucose-lowering agents have received widespread publicity. The objectives of this study were to evaluate the comparability in underlying cancer risk and patterns of cancer risk over time with different glucose-lowering agents.

METHODS

The General Practice Research Database (GPRD) was used to identify cohorts of new users. Cancer outcomes were obtained from the GPRD, Hospital Episode Statistics and cancer registries. Relative rates of cancer comparing different glucose-lowering agents were estimated using Poisson regression.

RESULTS

A total of 206,940 patients was identified. There was no difference in cancer risk and quartile for HbA(1c) value. There were differences in cancer incidence in the first 6 months after starting treatment (adjusted relative rate of 0.83 [95% CI 0.70, 0.99] with thiazolidinediones, 1.34 [95% CI 1.19, 1.51] with sulfonylureas and 1.79 [95% CI 1.53, 2.10] with insulin, compared with metformin). Insulin users had decreasing cancer incidence over time (adjusted relative rate of 0.58 [95% CI 0.50, 0.68] during months 6-24, relative rate of 0.50 [95% CI 0.42, 0.59] during months 25-60 and relative rate of 0.48 [95% CI 0.40, 0.59] during months 60+) compared with months 0-6 after starting insulin. Similar patterns were found with sulfonylureas and metformin. There were no increases over time with insulin glargine (A21Gly, B31Arg, B32Arg human insulin; relative rate of 0.70 [95% CI 0.52, 0.95], 0.77 [95% CI 0.56, 1.07] and 0.60 [95% CI 0.36, 1.02], respectively, for 6-24, 25-60 and >60 months).

CONCLUSIONS

These findings do not provide evidence of either beneficial or adverse effects of glucose-lowering agents on cancer risk and are consistent with changes in diabetes treatment in the few months prior to the diagnosis of cancer.

Do antidiabetic medications play a specific role in differentiated thyroid cancer compared to other cancer types?

The risk for differentiated thyroid cancer, like for many other types of cancer, is increased in obese individuals and people with intermediate hyperglycaemia. The incidence of all cancers, with the exception of thyroid cancer, is also increased in type 2 diabetes mellitus patients. The review compares the prevalence of thyroid carcinoma and other cancers in obese, people with intermediate hyperglycaemia and patients with diabetes and summarizes mode of action and anti-tumourigenic effect of common antidiabetic medications. The over-expression of dipeptidyl peptidase IV in the tumours, not seen in the other cancer types, is suggested as a potential reason for the unique situation in thyroid cancer.

Cross-talk between insulin and Wnt signaling in preadipocytes: role of Wnt co-receptor low density lipoprotein receptor-related protein-5 (LRP5)

Disturbed Wnt signaling has been implicated in numerous diseases, including type 2 diabetes and the metabolic syndrome. In the present study, we have investigated cross-talk between insulin and Wnt signaling pathways using preadipocytes with and without knockdown of the Wnt co-receptors LRP5 and LRP6 and with and without knock-out of insulin and IGF-1 receptors. We find that Wnt stimulation leads to phosphorylation of insulin signaling key mediators, including Akt, GSK3β, and ERK1/2, although with a lower fold stimulation and slower time course than observed for insulin. These Wnt effects are insulin/IGF-1 receptor-dependent and are lost in insulin/IGF-1 receptor double knock-out cells. Conversely, in LRP5 knockdown preadipocytes, insulin-induced phosphorylation of IRS1, Akt, GSK3β, and ERK1/2 is highly reduced. This effect is specific to insulin, as compared with IGF-1, stimulation and appears to be due to an inducible interaction between LRP5 and the insulin receptor as demonstrated by co-immunoprecipitation. These data demonstrate that Wnt and insulin signaling pathways exhibit cross-talk at multiple levels. Wnt induces phosphorylation of Akt, ERK1/2, and GSK3β, and this is dependent on insulin/IGF-1 receptors. Insulin signaling also involves the Wnt co-receptor LRP5, which has a positive effect on insulin signaling. Thus, altered Wnt and LRP5 activity can serve as modifiers of insulin action and insulin resistance in the pathophysiology of diabetes and metabolic syndrome.

Insulin use is not significantly predictive for prostate cancer mortality in diabetic patients: a 12-year follow-up study

What's known on the subject? and What does the study add? Even though a lower risk of prostate cancer has been reported in patients with diabetes, they may have a higher risk of cancer development involving the liver, pancreas, endometrium, colorectum, breast and bladder. Insulin may have mitogenic properties besides its metabolic function. However, whether exogenous insulin use for glycaemic control in diabetic patients could increase the risk of prostate cancer has rarely been studied. This is the first prospective follow-up study for up to 12 years to show that exogenous insulin use for glycaemic control in the diabetic patients is not significantly predictive for prostate cancer mortality.

OBJECTIVE

To evaluate whether insulin use in diabetic patients could be predictive for prostate cancer mortality.

PATIENTS AND METHODS

A total of 39 135 diabetic men aged ≥40 years from a nationally representative cohort were followed prospectively from 1995 to 2006 for prostate cancer mortality. Cox proportional hazards models were used to estimate the hazard ratios for the following independent variables: age, diabetes type, diabetes duration, body mass index, smoking, insulin use and area of residence. The models were created for patients aged ≥40 years and ≥65 years, separately; and before and after excluding patients with a duration between onset of diabetes and prostate cancer mortality <5 years.

RESULTS

A total of 105 diabetic men died of prostate cancer during follow-up. Age was the only significant risk factor. Insulin use was associated with an insignificantly higher risk of prostate cancer mortality ranging from 24% to 49%. When stratified by the duration of insulin use <5 and ≥5 years, a lack of significant association was also observed.

CONCLUSIONS

Insulin use in diabetic patients does not significantly predict the mortality from prostate cancer. Further confirmation in other ethnicities is needed.

The association of diabetes mellitus with liver, colon, lung, and prostate cancer is independent of hypertension, hyperlipidemia, and gout in Taiwanese patients

Studies have shown an association between diabetes and cancer in Western countries; but this, as well as the influence of associated metabolic factors, must be confirmed by a prospective study in other population groups. This study aimed to investigate whether the strong association of cancer and diabetes is independent from the influence of hypertension, dyslipidemia, and gout in the Taiwanese population. A total of 985,815 study subjects were identified from the National Health Insurance in 1997 and followed up from 1998 to 2009. The demographic characteristics between patients with diabetes and cancer, including age, sex, hypertension, dyslipidemia, and gout, were analyzed using the χ(2) test. Cox proportional hazard regression models were used to determine the independent effects of diabetes on the risks of cancer. A total of 104,343 diabetic patients were followed up from 1998 to 2009. After adjusting for sex, age, hypertension, dyslipidemia, and gout, the incidences of cancer at any site and in the liver, colon, lungs, and prostate in diabetic patients were independently higher, with risk ratios of 1.56 (95% confidence interval [CI], 1.43-1.71), 1.67 (95% CI, 1.39-2.01), 1.75 (95% CI, 1.49-2.06), 1.54 (95% CI, 1.26-1.88), and 1.56 (95% CI, 1.19-2.04), respectively. Only breast cancer did not show any clinical significance. There was an increased incidence of cancer at any site in the diabetic patients compared with nondiabetic subjects. The most common cancers were liver, colon, lung, breast, and prostate cancer; and except for breast cancer, their incidences increased independently of hypertension, dyslipidemia, and gout in patients with diabetes.

Mortality after incident cancer in people with and without type 2 diabetes: impact of metformin on survival

OBJECTIVE

Type 2 diabetes is associated with an increased risk of several types of cancer and with reduced survival after cancer diagnosis. We examined the hypotheses that survival after a diagnosis of solid-tumor cancer is reduced in those with diabetes when compared with those without diabetes, and that treatment with metformin influences survival after cancer diagnosis.

RESEARCH DESIGN AND METHODS

Data were obtained from >350 U.K. primary care practices in a retrospective cohort study. All individuals with or without diabetes who developed a first tumor after January 1990 were identified and records were followed to December 2009. Diabetes was further stratified by treatment regimen. Cox proportional hazards models were used to compare all-cause mortality from all cancers and from specific cancers.

RESULTS

Of 112,408 eligible individuals, 8,392 (7.5%) had type 2 diabetes. Cancer mortality was increased in those with diabetes, compared with those without (hazard ratio 1.09 [95% CI 1.06-1.13]). Mortality was increased in those with breast (1.32 [1.17-1.49]) and prostate cancer (1.19 [1.08-1.31]) but decreased in lung cancer (0.84 [0.77-0.92]). When analyzed by diabetes therapy, mortality was increased relative to nondiabetes in those on monotherapy with sulfonylureas (1.13 [1.05-1.21]) or insulin (1.13 [1.01-1.27]) but reduced in those on metformin monotherapy (0.85 [0.78-0.93]).

CONCLUSIONS

This study confirmed that type 2 diabetes was associated with poorer prognosis after incident cancer, but that the association varied according to diabetes therapy and cancer site. Metformin was associated with survival benefit both in comparison with other treatments for diabetes and in comparison with a nondiabetic population.

Does use of metformin protect against cancer in Type 2 diabetes mellitus?

BACKGROUND

Type 2 diabetes mellitus has been associated with an increased cancer risk, which can be modified by specific hypoglycemic drugs. In particular, metformin, the most frequently prescribed biguanide, is now considered a protective agent against cancer incidence and mortality in Type 2 diabetic patients.

AIMS

To review the potential associations between metformin use and cancer incidence and mortality and the possible biological links implicated in these associations.

MATERIALS AND METHODS

We searched English-language original investigations published through September 2011.

RESULTS

Metformin could block the mitogenic effects of insulin, but this effect does not entirely explain the reduction in cancer incidence. Metformin also plays a direct inhibition of cancer cell growth via the inhibitory effects of AMP-activated protein kinase on the mTOR pathway, which regulates cell growth and proliferation. Accordingly, many epidemiological studies have shown that metformin use is associated with a lower cancer incidence and mortality through a dose-response relationship, with greater exposure being associated with stronger risk reduction. Randomized clinical trials testing the effects of metformin on both recurrence and survival in early-stage breast cancer are on-going; these trials are based on pilot studies demonstrating an adjuvant effect of this drug in breast cancer.

CONCLUSIONS

Metformin is an inexpensive and safe drug, that may modify the increased cancer risk of Type 2 diabetic patients. On-going clinical trials will show whether this drug can enhance the effect of chemotherapy in the treatment of cancer.

Wnt/β-catenin signaling pathway and thioredoxin-interacting protein (TXNIP) mediate the "glucose sensor" mechanism in metastatic breast cancer-derived cells MDA-MB-231

In this study we investigated the effect of glucose on GSK3β and β-catenin expression and the involvement of the N-linked glycosylation and hexosamine pathways in the Wnt canonical pathway in response to in vitro conditions resembling normoglycemia (5  mmol) and hyperglycemia (20  mmol) in the metastatic breast cancer-derived cell line MDA-MB-231. We also investigated the relationship between this circuitry and the thioredoxin-interacting protein (TXNIP) regulation that seems to be related. MDA-MB-231 cells were grown either in 5 or 20  mM glucose chronically prior to plating. For glucose shift (5/20), cells were plated in 5  mM glucose and shifted to 20  mM at time 0. Both protein and mRNA levels for GSK3β but only the protein expression for β-catenin, were increased in response to high glucose. Furthermore, we assessed the response of GSK3β, β-catenin, and TXNIP to inhibition of the N-linked glycosylation, hexosamine, and Wnt pathways. Wnt signaling pathway activation was validated by specific reporter assay. We show that high levels of glucose regulate mRNA and protein expression of GSK3β, and consequently higher levels of activated β-catenin protein, which locates to the nucleus and is associated with increased levels of cyclin D1 expression. This event coincides with increased level of N-terminal Ser 9 phosphorylation of GSK3β protein. The inhibition of both the hexosamine pathway and N-linked glycosylation along with Wnt signaling pathway by sFRP1 and DKK1 is associated with significant decrease of the protein levels of GSK3β, β-catenin, and TXNIP RNA. Our work illuminates a novel and never described before function of this signaling pathway that relates glucose metabolism with redox regulation mechanism.

Self-rated health and mortality in individuals with diabetes mellitus: prospective cohort study

OBJECTIVES

To investigate whether low self-rated health (SRH) is associated with increased mortality in individuals with diabetes.

DESIGN

Population-based prospective cohort study.

SETTING

Enrolment took place between 1992 and 2000 in four centres (Bilthoven, Heidelberg, Potsdam, Umeå) in a subcohort nested in the European Prospective Investigation into Cancer and Nutrition.

PARTICIPANTS

3257 individuals (mean ± SD age was 55.8±7.6 years and 42% women) with confirmed diagnosis of diabetes mellitus.

PRIMARY OUTCOME MEASURE

The authors used Cox proportional hazards modelling to estimate HRs for total mortality controlling for age, centre, sex, educational level, body mass index, physical inactivity, smoking, insulin treatment, hypertension, hyperlipidaemia and history of myocardial infarction, stroke or cancer.

RESULTS

During follow-up (mean follow-up ± SD was 8.6±2.3 years), 344 deaths (241 men/103 women) occurred. In a multivariate model, individuals with low SRH were at higher risk of mortality (HR 1.38, 95% CI 1.10 to 1.73) than those with high SRH. The association was mainly driven by increased 5-year mortality and was stronger among individuals with body mass index of <25 kg/m(2) than among obese individuals. In sex-specific analyses, the association was statistically significant in men only. There was no indication of heterogeneity across centres.

CONCLUSIONS

Low SRH was associated with increased mortality in individuals with diabetes after controlling for established risk factors. In patients with diabetes with low SRH, the physician should consider a more detailed consultation and intensified support.

Insulin analogs and cancer

Today, insulin analogs are used in millions of diabetic patients. Insulin analogs have been developed to achieve more physiological insulin replacement in terms of time-course of the effect. Modifications in the amino acid sequence of the insulin molecule change the pharmacokinetics and pharmacodynamics of the analogs in respect to human insulin. However, these changes can also modify the molecular and biological effects of the analogs. The rapid-acting insulin analogs, lispro, aspart, and glulisine, have a rapid onset and shorter duration of action. The long-acting insulin analogs glargine and detemir have a protracted duration of action and a relatively smooth serum concentration profile. Insulin and its analogs may function as growth factors and therefore have a theoretical potential to promote tumor proliferation. A major question is whether analogs have an increased mitogenic activity in respect to insulin. These ligands can promote cell proliferation through many mechanisms like the prolonged stimulation of the insulin receptor, stimulation of the IGF-1 receptor (IGF-1R), prevalent activation of the extracellular-signaling-regulated kinase (ERK) rather than the protein kinase B (PKB/AKT) intracellular post-receptor pathways. Studies on in vitro models indicate that short-acting analogs elicit molecular and biological effects that are similar to those of insulin. In contrast, long-acting analogs behave differently. Although not all data are homogeneous, both glargine and detemir have been found to have a decreased binding to receptors for insulin but an increased binding to IGF-1R, a prevalent activation of the ERK pathway, and an increased mitogenic effect in respect to insulin. Recent retrospective epidemiological clinical studies have suggested that treatment with long-acting analogs (specifically glargine) may increase the relative risk for cancer. Results are controversial and methodologically weak. Therefore prospective clinical studies are needed to evaluate the possible tumor growth-promoting effects of these insulin analogs.

Diabetes and the risk for colorectal cancer

Diabetes mellitus has been reported to be associated with an increased risk for colorectal cancer. The review analyzes current epidemiological data on the association of diabetes and the risk for colorectal cancer. Hyperinsulinemia, hyperglycemia, and inflammation are suggested to play a key role in the pathophysiology of cancer in diabetes. Data regarding potential treatment-related risks, particularly in conjunction with the use of insulin and insulin analogues, are also presented. Furthermore, the impact of glycemic control and cardiorespiratory fitness on cancer prognosis is considered. Finally, the preventive potential of aspirin and other nonsteroidal anti-inflammatory drugs, and the recommendations concerning colonoscopy-screening are presented.

Risk of cancer in patients on insulin glargine and other insulin analogues in comparison with those on human insulin: results from a large population-based follow-up study

AIMS/HYPOTHESIS

Several publications suggest an association between certain types of insulin and cancer, but with conflicting results. We investigated whether insulin glargine (A21Gly,B31Arg,B32Arg human insulin) is associated with an increased risk of cancer in a large population-based cohort study.

METHODS

Data for this study were obtained from dispensing records from community pharmacies individually linked to hospital discharge records from 2.5 million individuals in the Netherlands. In a cohort of incident users of insulin, the association between insulin glargine and other insulin analogues, respectively, and cancer was analysed in comparison with human insulin using Cox proportional hazard models with cumulative duration of drug use as a time-varying determinant. The first hospital admission with a primary diagnosis of cancer was considered as the main outcome; secondary analyses were performed with specific cancers as outcomes.

RESULTS

Of the 19,337 incident insulin users enrolled, 878 developed cancer. Use of insulin glargine was associated with a lower risk of malignancies in general in comparison with human insulin (HR 0.75, 95% CI 0.71, 0.80). In contrast, an increased risk was found for breast cancer (HR 1.58, 95% CI 1.22, 2.05). Dose-response relationships could not be identified.

CONCLUSION/INTERPRETATION

Users of insulin glargine and users of other insulin analogues had a lower risk of cancer in general than those using human insulin. Both associations might be a consequence of residual confounding, lack of adherence or competing risk. However, as in previous studies, we demonstrated an increased risk of breast cancer in users of insulin glargine in comparison with users of human insulin.

Cancer mortality reduction and metformin: a retrospective cohort study in type 2 diabetic patients

AIMS

Few studies suggest that metformin decreases cancer mortality in type-2 diabetic patients (T2DP). We explored the association between the type and duration of antidiabetic therapies and cancer and other-than-cancer mortality in a T2DP cohort, taking into account the competing risks between different causes of death and multiple potential confounding effects. The mortality rates were compared with the general population from the same area.

METHODS

In 1995, all T2DP (n = 3685) at our diabetes clinic in Turin (∼12% of all T2DP in the city), without cancer at baseline, were identified. Vital status was assessed after a mean 4.5-year follow-up.

RESULTS

Metformin users had greater adiposity, while insulin users had more co-morbidities. All-cause- and cancer-related deaths occurred in: 9.2 and 1.6% of metformin users, 13.1 and 3.0% of sulfonylureas users and 26.8 and 4.8% of insulin users, respectively. In a Cox regression model for competing risks, adjusted for propensity score, metformin users showed a lower cancer mortality risk [hazard ratio (HR) = 0.56; 95% confidence interval (CI) 0.34-0.94], while insulin was positively associated with other-than-cancer mortality (HR = 1.56; 95%CI 1.22-1.99). Each 5-year metformin exposure was associated with a reduction in cancer death by 0.73, whereas every 5-year insulin exposure was associated with 1.25-fold increase in other-than-cancer death. Standardized mortality ratios for cancer and other-than-cancer mortality in metformin users were 43.6 (95%CI 25.8-69.0) and 99.1 (95%CI 79.3-122.5), respectively, in comparison with the general population.

CONCLUSIONS

Metformin users showed a lower risk of cancer-related mortality than not users or patients on diet only; this may represent another reason to choose metformin as a first-line therapy in T2DP.

Targeting the Insulin-Like Growth Factor (IGF) System Is Not as Simple as Just Targeting the Type 1 IGF Receptor

Increased signaling of the insulin-like growth factor (IGF) system via alterations in expression levels of its components has been demonstrated in various tumor types. Numerous experimental studies have supported the involvement of the IGF system signaling axis in tumor initiation and progression. These studies, combined with data that link alterations in the levels of circulating IGFs with cancer risk and prognosis, have focused on the IGF-1 receptor (IGF-1R) as a therapeutic target for patients with cancer. As a consequence, most therapeutic strategies have been designed to specifically inhibit IGF-1R but have for the most part ignored the insulin receptor (IR), based on concerns that targeting IR would lead to unacceptable toxicity both because of its role in physiologic metabolism and because we frequently try to oversimplify biologic complexity whenever we are urged to find practical, friendly solutions for clinical practice. Although this is an understandable and necessary starting point in the complex and long-lasting processes that leads to translational biology, the crude reality of the results obtained from phase I and II studies suggest a need for researchers to be humble and go back to the drawing board. Cancer research has substantially neglected the role of IR, and it remains unclear whether and to what extent avoiding the inhibition of IR has compromised the efficacy of anti-IGF-1R therapy. Clarifying its role might also help us take advantage of older drugs that could offer new perspectives in cancer care.

Diabetes and non-Hodgkin's lymphoma: analyses of prevalence and annual incidence in 2005 using the National Health Insurance database in Taiwan

BACKGROUND

The association between diabetes and non-Hodgkin's lymphoma (NHL) is rarely studied and the risk associated with insulin use is not known.

MATERIALS AND METHODS

The crude and age-standardized trends of NHL incidence in the general population from 1979 to 2007 were first calculated. NHL prevalence and annual incidence in 2005 were calculated in 329,198 insurants aged≥45 years from a random sample of 1,000,000 insurants of the National Health Insurance. The risk factors were evaluated using logistic regression.

RESULTS

NHL incidence trends increased significantly in either sex. A total of 1079 and 148 NHL cases were identified for prevalence and incidence analyses, respectively. The respective prevalence (per 100,000) for diabetic and nondiabetic subjects was 480.2 and 269.9 (P<0.01), and the respective incidence (per 100,000) was 70.9 and 35.3 (P<0.01). Odds ratio for diabetic versus nondiabetic subjects after adjustment for age, sex, occupation, and living region was 1.51 (95% confidence interval 1.33-1.71) for prevalence and 1.48 (1.06-2.06) for incidence. In diabetic patients, the adjusted odds ratio for insulin users versus nonusers was 1.63 (1.23-2.15) for prevalence and 2.52 (1.37-4.64) for incidence.

CONCLUSIONS

NHL incidence is increasing in Taiwan. Diabetes and insulin use are associated with a higher risk.

IGF1/insulin receptor kinase inhibition by BMS-536924 is better tolerated than alloxan-induced hypoinsulinemia and more effective than metformin in the treatment of experimental insulin-responsive breast cancer

Epidemiologic and experimental evidence suggest that a subset of breast cancer is insulin responsive, but it is unclear whether safe and effective therapies that target the insulin receptor (IR), which is homologous to oncogenes of the tyrosine kinase class, can be developed. We demonstrate that both pharmacologic inhibition of IR family tyrosine kinase activity and insulin deficiency have anti-neoplastic activity in a model of insulin-responsive breast cancer. Unexpectedly, in contrast to insulin deficiency, pharmacologic IR family inhibition does not lead to significant hyperglycemia and is well tolerated. We show that pharmacokinetic factors explain the tolerability of receptor inhibition relative to insulin deficiency, as the small molecule receptor kinase inhibitor BMS-536924 does not accumulate in muscle at levels sufficient to block insulin-stimulated glucose uptake. Metformin, which lowers insulin levels only in settings of hyperinsulinemia, had minimal activity in this normoinsulinemic model. These findings highlight the importance of tissue-specific drug accumulation as a determinant of efficacy and toxicity of tyrosine kinase inhibitors and suggest that therapeutic targeting of the IR family for cancer treatment is practical.

Molecular mechanisms of cancer development in obesity

The increasing incidence of obesity and its co-morbid conditions poses a great challenge to global health. In addition to cardiovascular disease and diabetes, epidemiological data demonstrate a link between obesity and multiple types of cancer. The molecular mechanisms underlying how obesity causes an increased risk of cancer are poorly understood. Obesity disrupts the dynamic role of the adipocyte in energy homeostasis, resulting in inflammation and alteration of adipokine (for example, leptin and adiponectin) signalling. Additionally, obesity causes secondary changes that are related to insulin signalling and lipid deregulation that may also foster cancer development. Understanding these molecular links may provide an avenue for preventive and therapeutic strategies to reduce cancer risk and mortality in an increasingly obese population.

High glucose promotes pancreatic cancer cell proliferation via the induction of EGF expression and transactivation of EGFR

Multiple lines of evidence suggest that a large portion of pancreatic cancer patients suffer from either hyperglycemia or diabetes, both of which are characterized by high blood glucose level. However, the underlying biological mechanism of this phenomenon is largely unknown. In the present study, we demonstrated that the proliferative ability of two human pancreatic cancer cell lines, BxPC-3 and Panc-1, was upregulated by high glucose in a concentration-dependent manner. Furthermore, the promoting effect of high glucose levels on EGF transcription and secretion but not its receptors in these PC cell lines was detected by using an EGF-neutralizing antibody and RT-PCR. In addition, the EGFR transactivation is induced by high glucose levels in concentration- and time-dependent manners in PC cells in the presence of the EGF-neutralizing antibody. These results suggest that high glucose promotes pancreatic cancer cell proliferation via the induction of EGF expression and transactivation of EGFR. Our findings may provide new insight on the links between high glucose level and PC in terms of the molecular mechanism and reveal a novel therapeutic strategy for PC patients who simultaneously suffer from either diabetes or hyperglycemia.

Is diabetes mellitus an independent risk factor for colon cancer and rectal cancer?

OBJECTIVES

Diabetes mellitus (DM) has been associated with an increased risk of colorectal cancer (CRC). The American College of Gastroenterology Guidelines for Colorectal Cancer Screening 2008 recommend that clinicians be aware of an increased CRC risk in patients with smoking and obesity, but do not highlight the increase in CRC risk in patients with DM. To provide an updated quantitative assessment of the association of DM with colon cancer (CC) and rectal cancer (RC), we conducted a meta-analysis of case-control and cohort studies. We also evaluated whether the association varied by sex, and assessed potential confounders including obesity, smoking, and exercise.

METHODS

We identified studies by searching the EMBASE and MEDLINE databases (from inception through 31 December 2009) and by searching bibliographies of relevant articles. Summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated with fixed- and random-effects models. Several subgroup analyses were performed to explore potential study heterogeneity and bias.

RESULTS

DM was associated with an increased risk of CC (summary RR 1.38, 95% CI 1.26-1.51; n=14 studies) and RC (summary RR 1.20, 95% CI 1.09-1.31; n=12 studies). The association remained when we limited the meta-analysis to studies that either controlled for smoking and obesity, or for smoking, obesity, and physical exercise. DM was associated with an increased risk of CC for both men (summary RR 1.43, 95% CI 1.30-1.57; n=11 studies) and women (summary RR 1.35, 95% CI 1.14-1.53; n=10 studies). For RC, there was a significant association between DM and cancer risk for men (summary RR 1.22, 95% CI 1.07-1.40; n=8 studies), but not for women (summary RR 1.09, 95% CI=0.99-1.19; n=8 studies).

CONCLUSIONS

These data suggest that DM is an independent risk factor for colon and rectal cancer. Although these findings are based on observational epidemiological studies that have inherent limitations due to diagnostic bias and confounding, subgroup analyses confirmed the consistency of our findings across study type and population. This information can inform risk models and specialty society CRC screening guidelines.

Urinary 8-oxo-7,8-dihydro-2'-deoxyguanosine as a biomarker in type 2 diabetes

The increasing prevalence of diabetes together with the associated morbidity and mortality calls for additional preventive and therapeutic strategies. New biomarkers that can be used in therapy control and risk stratification as alternatives to current methods are needed and can facilitate a more individualized and sufficient treatment of diabetes. Evidence derived from both epidemiological and mechanistic studies suggests that oxidative stress has an important role in mediating the pathologies of diabetic complications. A marker of intracellular oxidative stress that potentially could be used as a valuable biomarker in diabetes is the DNA oxidation marker 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG), which can be assessed noninvasively in the urine, with minimal discomfort for the patient. In this review the analytical validity of 8-oxodG is addressed by highlighting important methodological issues. The available epidemiological evidence regarding urinary 8-oxodG and type 2 diabetes is presented. A possible role for DNA oxidation in cancer development in type 2 diabetes patients is discussed, followed by an evaluation of the potential of urinary 8-oxodG as a clinical biomarker in type 2 diabetes.

Diabetes, diabetes therapies and cancer: what’s the link?

Diabetes and cancer are prevalent diseases that have a large global impact on health and healthcare resources. Epidemiological studies suggest that patients with diabetes are at a higher risk of developing certain types of cancers. This may be due to diabetes and cancer sharing common risk factors, but it is likely that any association is intricately linked by biological mechanisms, which are only starting to be unravelled. This is further complicated by emerging data that suggest that some diabetes therapies may predispose or promote development of certain cancers, while metformin appears to have anti-neoplastic effects. This review considers the evidence associating diabetes, diabetes therapies and cancer.

Type 2 diabetes mellitus and medications for type 2 diabetes mellitus are associated with risk for and mortality from cancer in a German primary care cohort

There is growing evidence that patients with type 2 diabetes mellitus have increased cancer risk. We examined the association between diabetes, cancer, and cancer-related mortality and hypothesized that insulin sensitizers lower cancer-related mortality. Participants in the Diabetes Cardiovascular Risk and Evaluation: Targets and Essential Data for Commitment of Treatment study, a nationwide cross-sectional and prospective epidemiological study, were recruited from German primary care practices. In the cross-sectional study, subjects with type 2 diabetes mellitus had a higher prevalence of malignancies (66/1308, 5.1%) compared to nondiabetic subjects (185/6211, 3.0%) (odds ratio, 1.64; 95% confidence interval, 1.12-2.41) before and after adjustment for age, sex, hemoglobin A(1c), smoking status, and body mass index. Patients on metformin had a lower prevalence of malignancies, comparable with that among nondiabetic patients, whereas those on any other oral combination treatment had a 2-fold higher risk for malignancies even after adjusting for possible confounders; inclusion of metformin in these regimens decreased the prevalence of malignancies. In the prospective analyses, diabetic patients in general and diabetic patients treated with insulin (either as monotherapy or in combination with other treatments) had a 2- and 4-fold, respectively, higher mortality rate than nondiabetic patients, even after adjustment for potential confounders (incidence of cancer deaths in patients with type 2 diabetes mellitus [2.6%] vs the incidence of cancer deaths in patients without type 2 diabetes mellitus [1.2%]). Our results suggest that diabetes and medications for diabetes, with the exception of the insulin sensitizer metformin, increase cancer risk and mortality.

Diabetes, pancreatic cancer and vitamin D. Is there a link?

The role of vitamin D is not merely limited to maintaining skeletal health but also extends to maintaining glucose homeostasis by preserving insulin secretion and sensitivity and thus deficiency of vitamin D plays an important role in aetiopathogenesis of T2 diabetes. In addition to its many other roles, vitamin D has recently been found to have growth inhibiting affects on pancreatic cancer cells. Ecological studies have shown that there exists an inverse correlation between sun exposure and death rates for pancreatic cancer. Since vitamin D has promising role in both type 2 diabetes mellitus and pancreatic cancer, its deficiency may be associated to any or both of these chronic diseases. The present review thus aims to find correlation between diabetes and pancreatic cancer and if vitamin D is a common link between the two.

Type of diabetes mellitus and the odds of Gleason score 8 to 10 prostate cancer

PURPOSE

It has been recently shown that diabetes mellitus (DM) is significantly associated with the likelihood of presenting with high-grade prostate cancer (PCa) or Gleason score (GS) 8 to 10; however, whether this association holds for both Type 1 and 2 DM is unknown. In this study we evaluated whether DM Type 1, 2, or both are associated with high-grade PCa after adjusting for known predictors of high-grade disease.

METHODS AND MATERIALS

Between 1991 and 2010, a total of 15,330 men diagnosed with PCa and treated with radiation therapy were analyzed. A polychotomous logistic regression analysis was performed to evaluate whether Type 1 or 2 DM was associated with odds of GS 7 or GS 8 to 10 compared with 6 or lower PCa, adjusting for African American race, age, prostate-specific antigen (PSA) level, and digital rectal examination findings.

RESULTS

Men with Type 1 DM (adjusted odds ratio [AOR], 2.05; 95% confidence interval [CI], 1.28-3.27; p = 0.003) or Type 2 DM (AOR, 1.58; 95% CI, 1.26-1.99; p < 0.001) were significantly more likely to be diagnosed with GS 8 to 10 PCa compared with nondiabetic men. However this was not true for GS 7, for which these respective results were AOR, 1.30; 95% CI, 0.93-1.82; p = 0.12 and AOR, 1.13; 95% CI, 0.98-1.32; p = 0.10.

CONCLUSION

Type 1 and 2 DM were associated with a higher odds of being diagnosed with Gleason score 8 to 10 but not 7 PCa. Pending validation, men who are diagnosed with Type I DM with GS 7 or lower should be considered for additional workup to rule out occult high-grade disease.

PGC1α promotes tumor growth by inducing gene expression programs supporting lipogenesis

Despite the role of aerobic glycolysis in cancer, recent studies highlight the importance of the mitochondria and biosynthetic pathways as well. PPARγ coactivator 1α (PGC1α) is a key transcriptional regulator of several metabolic pathways including oxidative metabolism and lipogenesis. Initial studies suggested that PGC1α expression is reduced in tumors compared with adjacent normal tissue. Paradoxically, other studies show that PGC1α is associated with cancer cell proliferation. Therefore, the role of PGC1α in cancer and especially carcinogenesis is unclear. Using Pgc1α(-/-) and Pgc1α(+/+) mice, we show that loss of PGC1α protects mice from azoxymethane-induced colon carcinogenesis. Similarly, diethylnitrosamine-induced liver carcinogenesis is reduced in Pgc1α(-/-) mice as compared with Pgc1α(+/+) mice. Xenograft studies using gain and loss of PGC1α expression showed that PGC1α also promotes tumor growth. Interestingly, while PGC1α induced oxidative phosphorylation and tricarboxylic acid cycle gene expression, we also observed an increase in the expression of two genes required for de novo fatty acid synthesis, ACC and FASN. In addition, SLC25A1 and ACLY, which are required for the conversion of glucose into acetyl-CoA for fatty acid synthesis, were also increased by PGC1α, thus linking the oxidative and lipogenic functions of PGC1α. Indeed, using stable (13)C isotope tracer analysis, we show that PGC1α increased de novo lipogenesis. Importantly, inhibition of fatty acid synthesis blunted these progrowth effects of PGC1α. In conclusion, these studies show for the first time that loss of PGC1α protects against carcinogenesis and that PGC1α coordinately regulates mitochondrial and fatty acid metabolism to promote tumor growth.

Diabetes causes multiple genetic alterations and downregulates expression of DNA repair genes in the prostate

The molecular impact of diabetes mellitus on prostate gland has not been elucidated. In this study, we performed a whole-genome cDNA microarray analysis using a streptozotocin-induced diabetic rat model to identify the effects of diabetes on the gene expression profiles in prostate. Our study shows that diabetes causes changes in the expression of multiple genes, particularly those related to cell proliferation and differentiation, oxidative stress, DNA damage repair, cell cycle checkpoints, angiogenesis and apoptosis. These findings were confirmed by real-time polymerase chain reaction and immunohistochemical staining using rat and human prostate tissue. We also used a cell culture model (human normal prostatic RWPE-1 cell line) to study the direct effect of high glucose. We found that high glucose caused increased intracellular oxidative stress and DNA damage, as well as downregulation of anti-oxidative enzymes and DNA damage repair genes MRE11 and XRCC3. Our findings provide important insights into understanding the pathogenesis of the diabetes-induced changes in prostate as well as identifying potential therapeutic targets for future studies.

Time-varying incidence of cancer after the onset of type 2 diabetes: evidence of potential detection bias

AIMS/HYPOTHESIS

Despite the vast body of epidemiological literature on the risk of cancer in people with diabetes, few studies have examined the pattern of cancer risk during different time windows following diabetes onset. The objective of the study was to examine the risks of site-specific cancer in people with incident type 2 diabetes during different time windows following diabetes onset.

METHODS

This was a population-based retrospective cohort study. The study period was 1 April 1994 to 31 March 2006; censoring occurred at 31 March 2006, at death or on departure from British Columbia, Canada. Using linked health databases, we identified incident cohorts with and without diabetes, who were matched by age, sex and index year. Following a minimum 2-year cancer washout period, first site-specific cancers were identified prospectively in both cohorts.

RESULTS

Within 3 months following diabetes onset, participants with diabetes had significantly increased risks of colorectal, lung, liver, cervical, endometrial, ovarian, pancreatic and prostate cancers. After the initial 3-month period, the risks for colorectal (HR 1.15, 95% CI 1.05, 1.25), liver (HR 2.53, 95% CI 1.93, 3.31) and endometrial (HR 1.58, 95% CI 1.28, 1.94) cancers remained significantly elevated compared with those without diabetes. The diabetes cohort remained at increased risk of pancreatic cancer in later years, but followed a different pattern: HR 3.71 at 3 months-1 year, 2.94 at 1-2 years, 1.78 at 2-3 years and 1.65 at 3-10 years (p value for all <0.01). After an initial period of elevated risk, men with type 2 diabetes subsequently had a decreased risk of prostate cancer (HR 0.82, 95% CI 0.76, 0.88).

CONCLUSIONS/INTERPRETATION

People with type 2 diabetes are at increased risk of select cancers; this risk is particularly elevated at the time of diabetes onset, which is likely to be due to increased ascertainment.

Type 2 diabetes mellitus and colorectal cancer: meta-analysis on sex-specific differences

Although there is consent concerning a higher risk for colorectal cancer (CRC) amongst patients with type 2 diabetes mellitus (T2DM), there remains uncertainty regarding potential sex differences in the strength of this association. We reviewed and summarised epidemiological studies assessing the sex-specific association of T2DM with the risk for CRC. All relevant studies published until 14th February 2011 were identified by a systematic search of MEDLINE, EMBASE, BIOSIS Previews and ISI Web of Knowledge databases and cross-referencing. We included observational studies that reported relative risk (RR) or odds ratio (OR) estimates with 95% confidence intervals (CIs) for the association between T2DM and CRC. Two authors independently extracted data and assessed study quality of each study in a standardised manner. Study-specific estimates were pooled for both sexes separately using random-effects models. A total of 29 eligible studies were used for meta-analysis. Overall estimates of relative risk (RR) were very similar amongst men (RR=1.29; 95%-confidence interval (CI): 1.19-1.140) and women (RR=1.34; 95%-CI: 1.22-1.47). In both men and women, risk estimates from case-control studies were slightly higher than those from cohort studies. Overall, T2DM is associated with a moderate increase in CRC risk in both men and women.

Insulin receptor and cancer

The widespread epidemic of obesity and type 2 diabetes has raised concern for the impact of these disorders as risk factors for cancer and has renewed the interest for studies regarding the involvement of hyperinsulinemia and insulin receptor (IR) in cancer progression. Overexpression of IR in cancer cells may explain their increased sensitivity to hyperinsulinemia. Moreover, IR isoform A (IR-A) together with autocrine production of its ligand IGF2 is emerging as an important mechanism of normal and cancer stem cell expansion and is a feature of several malignancies. De novo activation of the IR-A/IGF2 autocrine loop also represents a mechanism of resistance to anticancer therapies. Increasing knowledge of the IR role in cancer has important implications for cancer prevention, which should include control of insulin resistance and hyperinsulinemia in the population and meticulous evaluation of new antidiabetic drugs for their metabolic:mitogenic ratio. We are now aware that several anticancer treatments may induce or worsen insulin resistance that may limit therapy efficacy. Future anticancer therapies need to target the IR-A pathway in order to inhibit the tumor promoting effect of IR without impairing the metabolic effect of insulin.

Diabetes, gestational diabetes and the risk of cancer in women: epidemiologic evidence and possible biologic mechanisms

At present, more than 10% of adult American women are diagnosed with diabetes mellitus (DM). As the prevalence of the disease increases, there is greater interest in the relationship between DM and other major health issues, such as cancer - one of the leading causes of death in the western world. This paper reviews the literature on the relationship between Type 2 DM and different types of cancer among women. We discuss the possible biological mechanisms that may link diabetes and cancer, important confounders, shared risk factors and a short review of the epidemiologic literature on the association between Type 2 DM and cancer of specific organs (pancreas, liver, colorectal, bladder, endometrial, non-Hodgkin's lymphoma and breast). We also examine the association between gestational diabetes, a closely related risk factor for DM in women, and subsequent risk of cancer. Cancer survival of diabetic women is also briefly discussed. The paper concludes with an agenda for future research targeting the relationship between diabetes and cancer.

Categories of glucose tolerance and continuous glycemic measures and mortality

We investigated the association of undiagnosed diabetes, previously known diabetes and prediabetes (WHO 1999 classification) with all-cause and cause-specific mortality in an older German population. Previous study results for mortality in patients with very low levels of HbA1c, fasting plasma glucose (FPG), and 2-h plasma glucose (2hPG) are still inconclusive. Thus we have extended the analyses to continuous measures of glycemia. A total of 1,466 subjects aged 55-74 years from the population-based KORA survey S4 (conducted from 1999 to 2001) were included in our observational mortality study (152 subjects with previously known diabetes, and 1,314 further subjects who underwent oral glucose tolerance tests). Mortality was followed up for a maximum of 10.0 years (median follow-up 8.8 years). A total of 180 (12.3%) of the 1,466 subjects have died during the follow-up period. The age- and sex-adjusted hazard ratios for all-cause mortality were 2.6 (95%CI, 1.7-3.8) for known diabetes, 2.8 (95%CI, 1.7-4.4) for undiagnosed diabetes, and 1.1 (95%CI, 0.8-1.7) for prediabetes [reference: normal glucose tolerance (NGT)]. After multivariable adjustment, undiagnosed diabetes was associated with 3.0-fold increased cancer mortality, 1.1-fold increased cardiovascular mortality, and 4.7-fold increased non-cancer, non-cardiovascular mortality compared with NGT. For HbA1c, FPG, and 2hPG, J-shaped associations with all-cause mortality were observed. Undiagnosed diabetes is associated with increased all-cause, cancer, and non-cancer non-cardiovascular mortality, but not with cardiovascular mortality in this older population. All-cause mortality in undiagnosed diabetes is similar to that in previously known diabetes but much higher than mortality in prediabetes and NGT.

Targeting AMP-activated protein kinase in adipocytes to modulate obesity-related adipokine production associated with insulin resistance and breast cancer cell proliferation

BACKGROUND

Adipokines, e.g. TNFα, IL-6 and leptin increase insulin resistance, and consequent hyperinsulinaemia influences breast cancer progression. Beside its mitogenic effects, insulin may influence adipokine production from adipocyte stromal cells and paracrine enhancement of breast cancer cell growth. In contrast, adiponectin, another adipokine is protective against breast cancer cell proliferation and insulin resistance.AMP-activated protein kinase (AMPK) activity has been found decreased in visceral adipose tissue of insulin-resistant patients. Lipopolysaccharides (LPS) link systemic inflammation to high fat diet-induced insulin resistance. Modulation of LPS-induced adipokine production by metformin and AMPK activation might represent an alternative way to treat both, insulin resistance and breast cancer.

METHODS

Human preadipocytes obtained from surgical biopsies were expanded and differentiated in vitro into adipocytes, and incubated with siRNA targeting AMPKalpha1 (72 h), LPS (24 h, 100 μg/ml) and/or metformin (24 h, 1 mM) followed by mRNA extraction and analyses. Additionally, the supernatant of preadipocytes or derived-adipocytes in culture for 24 h was used as conditioned media to evaluate MCF-7 breast cancer cell proliferation.

RESULTS

Conditioned media from preadipocyte-derived adipocytes, but not from undifferentiated preadipocytes, increased MCF-7 cell proliferation (p < 0.01). Induction of IL-6 mRNA by LPS was reduced by metformin (p < 0.01), while the LPS-induced mRNA expression of the naturally occurring anti-inflammatory cytokine interleukin 1 receptor antagonist was increased (p < 0.01). Silencing of AMPKalpha1 enhanced LPS-induced IL-6 and IL-8 mRNA expression (p < 0.05).

CONCLUSIONS

Adipocyte-secreted factors enhance breast cancer cell proliferation, while AMPK and metformin improve the LPS-induced adipokine imbalance. Possibly, AMPK activation may provide a new way not only to improve the obesity-related adipokine profile and insulin resistance, but also to prevent obesity-related breast cancer development and progression.

Diabetes and cancer: Looking at the multiligand/RAGE axis

The association between diabetes and hyperglycemia and the associated increased risk of several solid and hematologic malignancies has been the subject of investigation for many years. Although the association is not fully understood, current knowledge clearly indicates that diabetes may influence malignant cell transformation by several mechanisms, including hyperinsulinemia, hyperglycemia and chronic inflammation. In this context, the receptor for advanced glycation end-products (RAGE) has emerged as a focal point in its contribution to malignant transformation and tumor growth. We highlight how RAGE, once activated, as it manifests itself in conditions such as diabetes or hyperglycemia, is able to continuously bring about an inflammatory milieu, thus supporting the contribution of chronic inflammation to the development of malignancies.

Cancer incidence in type 2 diabetes patients - first results from a feasibility study of the D2C cohort

BACKGROUND

A large prospective study in patients with type 2 diabetes (T2D), the German D2C cohort, is presently being enumerated to investigate risk factors of incident cancer in diabetic patients.

STUDY SETTING

A disease management program was offered, on a voluntary basis, to all T2D patients who were members of a statutory health insurance fund in Germany. This first feasibility report uses data from 26.742 T2D patients, who were 40 to 79 years old, resided in the Muenster District, and who were enrolled between June 2003 and July 2008. Cancer cases were identified through the regional Cancer Registry.

METHODS

Invasive cancer cases were identified using probabilistic record linkage procedures and pseudonymised personal identifiers. Censoring date was December 31, 2008. We included only first cancers, leaving 12.650 male and 14.092 female T2D with a total of 88.778 person-years (py). We computed standardised incidence ratios (SIR) for external comparisons and we employed Cox regression models and hazard ratios (HR) within the cohort.

RESULTS

We identified 759 first cancers among male T2D patients (18.7 per 1,000 py) and 605 among females (12.7 per 1,000 py). The risk of any incident cancer in T2D was raised (SIR = 1.14; 95% confidence interval [1.10 - 1.21]), in particular for cancer of the liver (SIR = 1.94 [1.15 - 2.94]) and pancreas (SIR = 1.45 [1.07-1.92]). SIRs decreased markedly with time after T2D diagnosis. In Cox models, adjusting for diabetes duration, body mass index and sex, insulin therapy was related to higher cancer risk (HR = 1.25 [1.17 - 1.33]). No effect was seen for metformin.

DISCUSSION

Our study demonstrates feasibility of record linkage between DMP and cancer registries. These first cohort results confirm previous reports. It is envisaged to enhance this cohort by inclusion of further regions of the state, expansion of the follow-up times, and collection of a more detailed medication history.

Diabetes, treatments for diabetes and their effect on cancer incidence and mortality: attempts to disentangle the web of associations

The association between type 2 diabetes and some types of cancer is well established and the complexity of this association is receiving increasing recognition. Many factors influence the risk of both diabetes and cancer including age, sex, ethnicity, socioeconomic status, obesity/insulin resistance, diet (including alcohol intake), physical activity levels and smoking history. The presence of diabetes may influence the uptake of cancer screening. Using an experimental approach to investigate the effect of better control of diabetes is helpful in assessing whether hyperglycaemia has a causal relationship with cancer. Diabetes treatments may influence the risk of cancer independently of their effect on glycaemia and complicate investigation of the association between diabetes and cancer. This article discusses the complexity involved in attempting to clarify the factors that contribute to the associations between diabetes, hyperglycaemia, diabetes treatment and cancer.