Diabetes mellitus and the risk of cancer: results from a large-scale population-based cohort study in Japan

Diabetes mellitus and risk of gastric cancer: a systematic review and meta-analysis of observational studies

AIM

Increasing evidence suggests that a history of diabetes may be involved in the development of various sites of cancer. However, the association of diabetes and risk of gastric cancer (GC) remains unclear.

METHODS

We identified studies by a literature search of MEDLINE (from 1 January 1966), Web of Science (from 1 January 1994), and EMBASE (from 1 January 1974 through 31 May 2011), and by searching the reference lists of pertinent articles. All data were extracted independently by two investigators using a standardized data abstraction tool. Summary relative risks (SRRs) with 95% confidence intervals (CIs) were calculated with a random-effects model. Between-study heterogeneity was assessed using the Cochran's Q and I statistics.

RESULTS

A total of 21 studies (four case-control studies, 17 cohort studies) were included in this meta-analysis. Analysis of these 21 studies found that compared with nondiabetic individuals, diabetic individuals had a similar risk of GC (SRRs, 1.09; 95% CI: 0.98-1.22). There was strong evidence of heterogeneity among these studies (P<0.001, I²=81.2%). A subgrouped analysis found that diabetic women had 18% increased risk of GC (SRRs, 1.18; 95% CI: 1.01-1.39), whereas it was not the case with diabetic men. No significant public bias was found in this study.

CONCLUSION

These findings of this systematic review indicate that compared with nondiabetic individuals, diabetic women have an 18% increased risk of GC development. However, diabetic men have a similar risk of GC.

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.

Metabolic syndrome is associated with gastric dysplasia

OBJECTIVE

Recent studies have shown an association between metabolic syndrome (MetS) and gastric cancer. This study was carried out to assess the effect of MetS on gastric dysplasia in a Korean population presenting for health check-ups.

METHODS

We conducted a retrospective, case-control study on gastric dysplasia between November 2003 and August 2009 at the health screening center. A gastric dysplasia group (N=128) and age-matched, gender-matched control group (N=358) were included. A total of 486 Korean patients aged 20 years or above were assessed for BMI, waist circumference, blood pressure, total cholesterol, low density lipoprotein (LDL)-cholesterol, high density lipoprotein-cholesterol, triglycerides, serum glucose, and HbA1c.

RESULTS

In the univariate analysis, fasting glucose, BMI, and the presence of MetS were significant factors associated with the risk of gastric dysplasia. In the multivariate analysis, four of the variables studied (fasting glucose, total cholesterol, LDL-cholesterol, and MetS) had a statistically significant relationship with gastric dysplasia. The risk of gastric dysplasia was associated with modest glucose levels [glucose 100-125 mg/dl; age-adjusted and gender-adjusted relative risk (RR), 2.261; 95% confidence interval (CI), 1.147-4.457; P=0.019], higher total cholesterol levels (total cholesterol ≥240 mg/dl; RR, 6.299; 95% CI, 1.277-31.076; P=0.024), modest LDL-cholesterol levels (LDL 130-159 mg/dl; RR, 0.250; 95% CI, 0.069-0.903; P=0.034), and the presence of MetS (MetS ≥3 components; RR, 2.177; 95% CI, 1.082-4.379; P=0.029).

CONCLUSION

Our findings suggest that MetS is associated with gastric dysplasia in the general Korean population.

Diabetes mellitus and incidence and mortality of colorectal cancer: a systematic review and meta-analysis of cohort studies

Increasing evidence suggests that a history of diabetes mellitus (DM) may be associated with an increased risk of colorectal cancer (CRC). To provide a quantitative assessment of the association between DM and risk of CRC, We evaluated the relation between DM and incidence and mortality of CRC in a systematic review of cohort studies. Full publications of cohort studies were identified in MEDLINE, EMBASE and Science Citation Index Expanded, through February 28, 2011. Summary relative risks (SRRs) with 95% confidence intervals (CIs) were summarized using a random-effects model. Between-study heterogeneity was assessed using the Cochran's Q and I2 statistics. A total of 41 cohort studies (35 articles) were included in this systematic review. Combining 30 cohort studies which presented results on diabetes and CRC incidence, diabetes was associated with an increased incidence of CRC (SRRs 1.27, 95% CI: 1.21-1.34), with evident heterogeneity among studies (P=0.002, I2=48.4%). Subgroup analysis and meta-regression analysis by controlling the confounders showed that the increased incidence of CRC was independent of geographic locations, sex, family history of colorectal cancer, smoking, physical activity and body mass index. Diabetes was also positively associated with CRC mortality (SRR 1.20, 95% CI: 1.03-1.40), with evidence of heterogeneity between studies (P<0.001, I2=81.4%). Results from this systematic review support that compared to non-diabetic individuals, diabetic individuals have an increased risk of CRC.

Diabetes and thyroid cancer risk in the National Institutes of Health-AARP Diet and Health Study

BACKGROUND

We hypothesized that diabetes may play a role in thyroid cancer risk due to the parallel secular rise in diabetes prevalence and morbidity in the United States, the higher prevalence of thyroid disorders among diabetics compared with the general population, and the potential roles of metabolic syndrome, obesity, and diabetes as precipitating factors in cancer development.

METHODS

We assessed the association between self-reported diabetes and the risk of differentiated thyroid cancer in the NIH-AARP Diet and Health Study, a prospective cohort of 200,556 women and 295,992 men, 50-71 years of age, in 1995-1996. Diabetes status and information on potential confounders was ascertained using a self-administered questionnaire. During an average of 10 years of follow-up, 585 thyroid cancer cases were identified. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI) for thyroid cancer and thyroid cancer subtypes in men and women according to diabetes status.

RESULTS

Nine percent of the total baseline cohort reported a history of diabetes (7% of women, 10% of men). A nonsignificant 25% increase in thyroid cancer risk (HR = 1.25; 95% CI: 0.95-1.64) was associated with diabetes. Among women, the risk was significantly increased (HR = 1.46, 95% CI: 1.01-2.10). The risk was not elevated among men (HR = 1.04, 95% CI: 0.69-1.58). In this cohort, diabetic women with differentiated thyroid cancer were at somewhat higher risk of follicular thyroid cancer (HR = 1.92; 95% CI: 0.86-4.27) than papillary thyroid cancer (HR = 1.25; 95% CI: 0.80-1.97).

CONCLUSION

This study lends support to the hypothesis that diabetes increases the risk of differentiated thyroid cancer.

Update: Hypogonadotropic hypogonadism in type 2 diabetes and obesity

Studies over the last few years have clearly established that at least 25% of men with type 2 diabetes have subnormal free testosterone concentrations in association with inappropriately low LH and FSH concentrations. Another 4% have subnormal testosterone concentrations with elevated LH and FSH concentrations. The Endocrine Society, therefore, now recommends the measurement of testosterone in patients with type 2 diabetes on a routine basis. The subnormal testosterone concentrations are not related to glycosylated hemoglobin or duration of diabetes, but are associated with obesity, very high C-reactive protein concentrations, and mild anemia. In addition, subnormal testosterone concentrations in these men are associated with a two to three times elevated risk of cardiovascular events and death in two early studies. Short-term studies of testosterone therapy in hypogonadal men with type 2 diabetes have demonstrated an increase in insulin sensitivity and a decrease in waist circumference. However, the data on the effect of testosterone replacement on glycemic control and cardiovascular risk factors such as cholesterol and C-reactive protein concentrations are inconsistent. As far as sexual function is concerned, testosterone treatment increases libido but does not improve erectile dysfunction and thus, phosphodiesterase inhibitors may be required. Trials of a longer duration are clearly required to definitively establish the benefits and risks of testosterone replacement in patients with type 2 diabetes and low testosterone.

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.

Influence of obesity and other risk factors on survival outcomes in patients undergoing pancreaticoduodenectomy for pancreatic cancer

OBJECTIVES

Established risk factors for the development of pancreatic cancer include tobacco use, family history of pancreatic cancer, personal history of diabetes, and obesity. The impact of risk factors on prognosis in patients with pancreatic cancer, particularly obesity, has recently become controversial.

METHODS

We conducted a retrospective analysis of patients with pancreatic adenocarcinoma who underwent pancreaticoduodenectomy between 1995 and 2009. Patients were categorized by body mass index (BMI) as normal (18.5-24.9 kg/m), overweight (25-29.9 kg/m), or obese (≥30 kg/m). Univariate analysis was performed to evaluate the association of obesity and other risk factors on overall survival.

RESULTS

Of the 355 patients evaluated, 149 (42.0%) had normal BMI, 131 (36.9%) were overweight, and 75 (21.1%) were obese. Overall survival for normal, overweight, and obese groups was 17.3 months (95% confidence interval [CI], 14.2-20.8 months), 20.0 months (95% CI, 16.6-23.6 months), and 22.1 months (95% CI, 16.5-36.4 months), respectively (P = 0.58). Hazard ratios for tobacco use, family history of pancreatic cancer, and history of diabetes were 1.07, 1.38, and 0.87, respectively.

CONCLUSIONS

Obesity and other risk factors have no impact on overall survival in patients with adenocarcinoma after pancreaticoduodenectomy. Further studies investigating the relationship between risk factors and their prognostic significance in patients with pancreatic cancer are warranted.

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.

Increased risk of hepatocellular carcinoma in patients with diabetes mellitus: a systematic review and meta-analysis of cohort studies

In recent years, increasing evidence has suggested a strong association between diabetes mellitus (DM) and hepatocellular carcinoma (HCC). To provide a quantitative assessment of this association, we performed a systematic review and meta-analysis of cohort studies. We collected studies through a literature search of Medline from January 1, 1966 and EMBASE from January 1, 1974, through July 31, 2010. Summary relative risks (SRRs) with their corresponding 95% confidence intervals (CIs) were calculated using a random-effects model. A total of 25 cohort studies that met our inclusion and exclusion criteria were included in our analysis. Among these, 18 studies showed that DM was associated with an increased incidence of HCC (SRRs = 2.01, 95% CI: 1.61-2.51), compared with individuals without DM. There was a statistically significant heterogeneity among these studies (Q = 136.68, p < 0.001, I(2) = 87.6%). Analyses subgrouped by controlling confounders revealed that the increased incidence of HCC was independent of geographic location, alcohol consumption, history of cirrhosis, or infections with hepatitis B (HBV) or hepatitis C virus (HCV). In addition, DM was also positively associated with HCC mortality (SRR = 1.56; 95% CI: 1.30-1.87), with no significant evidence of heterogeneity among studies (Q = 1.16, p = 0.56, I(2) =0%). There were no significant publication bias (p = 0.79 for Egger's regression asymmetry test). These findings strongly support a positive association between DM and increased risk of HCC in both males and females.

Pancreatogenic diabetes: special considerations for management

BACKGROUND/AIMS

Pancreatogenic, or type 3c, diabetes (T3cDM) occurs due to inherited or acquired pancreatic disease or resection. Although similar to the more prevalent type 1 and type 2 diabetes, pancreatogenic diabetes has a unique pattern of hormonal and metabolic characteristics and a high incidence of pancreatic carcinoma in the majority of patients with T3cDM. Despite these differences, no guidelines for therapy have been described.

METHODS

Published studies on the prevalence, pathophysiology, and cancer associations of T3cDM were reviewed. The recent studies on the protective role and mechanism of metformin therapy as both an anti-diabetic and anti-neoplastic agent were reviewed, and studies on the cancer risk of other anti-diabetic drugs were surveyed.

RESULTS

T3cDM accounts for 5-10% of Western diabetic populations and is associated with mild to severe disease. Hepatic insulin resistance is characteristic of T3cDM and is caused by deficiencies of both insulin and pancreatic polypeptide. 75% of T3cDM is due to chronic pancreatitis, which carries a high risk for pancreatic carcinoma. Insulin and insulin secretagogue treatment increases the risk of malignancy, whereas metformin therapy reduces it. Pancreatic exocrine insufficiency associated with T3cDM contributes to nutritional deficiencies and the development of metabolic bone disease.

CONCLUSIONS

Until consensus recommendations are reached, the glycemic treatment of T3cDM should avoid insulin and insulin secretagogues if possible. Metformin should be the first line of therapy, and continued if insulin treatment must be added for adequate glucose control. Pancreatic enzyme therapy should be added to prevent secondary nutritional and metabolic complications. and IAP.

Intensive glucose control and risk of cancer in patients with type 2 diabetes

AIMS/HYPOTHESIS

Type 2 diabetes has been associated with an increased risk of cancer. This study examines the effect of more vs less intensive glucose control on the risk of cancer in patients with type 2 diabetes.

METHODS

All 11,140 participants from the Action in Diabetes and Vascular Disease: Preterax and Diamicron-MR Controlled Evaluation (ADVANCE) trial (ClinicalTrials.gov NCT00145925) were studied. Cancer incidence and cancer mortality was compared in groups randomised to intensive or standard glucose control. Information on events during follow-up was obtained from serious adverse event reports and death certificates. HRs (95% CI) were calculated for all cancers, all solid cancers, cancer deaths and site-specific cancers.

RESULTS

After a median follow-up of 5 years, 363 and 337 cancer events were reported in the intensive and standard control groups, respectively (incidence 1.39/100 person-years [PY] and 1.28/100 PY; HR 1.08 [95% CI 0.93-1.26]). The incidences of all solid cancers and cancer deaths were 1.25/100 PY and 0.55/100 PY in the intensive group and 1.15/100 PY and 0.63/100 PY in the standard group (HR 1.09[95% CI 0.93–1.27] for solid cancers, and 0.88 [0.71–1.10] for cancer death) [corrected].Across all the major organ systems studied, no significant differences in the cancer incidences were observed in the intensive and standard control groups.

CONCLUSIONS/INTERPRETATIONS

More intensive glucose control achieved with a regimen that included greater use of gliclazide, insulin, metformin and other agents, did not affect the risk of cancer events or death in patients with type 2 diabetes.

Cancer risk in type 2 diabetes mellitus: metabolic links and therapeutic considerations

Type 2 diabetes mellitus (DM2) is increasing in incidence, creating worldwide public health concerns and impacting morbidity and mortality rates. An increasing number of studies have demonstrated shared associations between DM2 and malignancy, including key clinical, biochemical, and metabolic commonalities. This paper will attempt to explore the relationship between the various types of cancer and diabetes, the common metabolic pathways underlying cancer development, and the potential impact of various antidiabetes therapies on cancer risk.

Diabetes and cancer: is diabetes causally related to cancer?

Diabetes mellitus is a serious and growing health problem worldwide and is associated with severe acute and chronic complications. Moreover, epidemiologic evidence suggests that people with diabetes are at significantly higher risk for many forms of cancer. Several studies indicate an association between diabetes and the risk of liver, pancreas, endometrium, colon/rectum, breast, and bladder cancer. Mortality is also moderately increased in subjects with diabetes. Common risk factors such as age, obesity, physical inactivity and smoking may contribute to increased cancer risk in diabetic patients. Hyperinsulinemia most likely favors cancer in diabetic patients as insulin is a growth factor with pre-eminent metabolic as well as mitogenic effects, and its action in malignant cells is favored by mechanisms acting at both the receptor and post-receptor level. The effect of diabetes treatment drugs, aside from metformin, on cancer is not conclusive. In order to fight the perfect storm of diabetes and cancer, strategies to promote primary prevention and early detection of these conditions are urgently needed.

Diabetes mellitus and incidence of kidney cancer: a meta-analysis of cohort studies

AIMS/HYPOTHESIS

Diabetes is associated with increased risk of cancer at several sites, but its association with cancer of the kidney is unclear. We performed a systematic review with meta-analysis to examine the association between diabetes and incidence of kidney cancer.

METHODS

Pertinent studies were identified by searching PubMed (from January 1966 to December 2010) and reviewing the reference lists of relevant articles. We included cohort studies reporting RR estimates and 95% CI (or data to calculate them) of the association between diabetes and kidney cancer incidence. Summary RRs were calculated using a random-effects model.

RESULTS

Nine cohort studies met the inclusion criteria. Analysis of all studies showed that compared with individuals without diabetes, patients with diabetes had a statistically significant increased risk of kidney cancer (RR 1.42, 95% CI 1.06-1.91). There was heterogeneity among studies (p < 0.001 for heterogeneity). The association was stronger in women (RR 1.70, 95% CI 1.47-1.97) than in men (RR 1.26, 95% CI 1.06-1.49). When restricting the analysis to studies that had adjusted for body mass index (n = 3) or cigarette smoking (n = 3), the RRs were 1.12 (95% CI 0.99-1.27) and 1.29 (95% CI 1.05-1.58), respectively.

CONCLUSIONS/INTERPRETATION

This meta-analysis indicates a positive association between diabetes and risk of kidney cancer. Future research should attempt to establish whether this association is causal.

Prognostic influence of metformin as first-line chemotherapy for advanced nonsmall cell lung cancer in patients with type 2 diabetes

BACKGROUND

It has been reported that antidiabetic drugs affect the risk of cancer and the prognosis of patients with diabetes, but few studies have demonstrated the influence of different antidiabetic agents on outcomes after anticancer therapy among patients with cancer. The objective of this study was to evaluate the influence of the antidiabetic drugs metformin and insulin on the prognosis of patients with advanced nonsmall cell lung cancer (NSCLC) plus type 2 diabetes who received first-line chemotherapy.

METHODS

Data on patients with NSCLC who had diabetes from 5 hospitals in China during January 2004 to March 2009 were reviewed retrospectively. Ninety-nine patients were included in the final analysis. The influence of metformin and insulin on chemotherapy response rates and survival in these patients was evaluated.

RESULTS

Chemotherapy with metformin (Group A) produced superior results compared with insulin (Group B) and compared with drugs other than metformin and insulin (Group C) in terms of both progression-free survival (PFS) (8.4 months vs 4.7 months vs 6.4 months, respectively; P = .002) and overall survival (OS) (20.0 months vs 13.1 months vs 13.0 months, respectively; P = .007). Although no significant differences in the response rate (RR) were observed between these 3 groups, when groups B and C (ie, the nonmetformin group) were combined, there was a tendency for better disease control in Group A than that in nonmetformin group. No significant difference in survival was observed between chemotherapy with insulin (Group B) versus other drugs (Group C).

CONCLUSIONS

The current data suggested that metformin may improve chemotherapy outcomes and survival for patients who have NSCLC with diabetes.

Metabolic syndrome and risk of bladder cancer: prospective cohort study in the metabolic syndrome and cancer project (Me-Can)

There are little data on the putative association between factors in the metabolic syndrome (MetS) and risk of bladder cancer. In the Metabolic Syndrome and Cancer project (Me-Can), measurements of height, weight, blood pressure and circulating levels of glucose, cholesterol, and triglycerides had been collected from 578,700 subjects in cohorts in Norway, Austria, and Sweden. We used Cox proportional hazard models to calculate relative risks (RRs) of bladder cancer by exposures divided into quintiles, in categories according to the World Health Organisation (WHO) and as a continuous standardized variable (z-score with mean = 0 and standard deviation = 1) for each separate component and its standardized sum, a composite MetS score. RRs were corrected for random error in measurements. During a mean follow-up of 11.7 years (SD = 7.6), 1,587 men and 327 women were diagnosed with bladder cancer. Significant associations with risk were found among men per one unit increment of z-score for blood pressure, RR = 1.13 (95% CI 1.03-1.25), and the composite MetS score, RR = 1.10 (95% CI 1.01-1.18). Among women, glucose was nonsignificantly associated with risk, RR = 1.41 (95% CI 0.97-2.06). No statistically significant interactions were found between the components in the MetS in relation to bladder cancer risk. Hypertension and a composite MetS score were significantly but modestly associated with an increased risk of bladder cancer among men and elevated glucose was associated with a nonsignificant increase in risk among women.

Impact of radiation and hepatitis virus infection on risk of hepatocellular carcinoma

In cohort studies of atomic bomb survivors and Mayak nuclear facility workers, radiation-associated increases in liver cancer risk were observed, but hepatitis B virus (HBV) and hepatitis C virus (HCV) infections were not taken strictly into account. We identified 359 hepatocellular carcinoma (HCC) cases between 1970 and 2002 in the cohort of atomic bomb survivors and estimated cumulative incidence of HCC by radiation dose. To investigate contributions of radiation exposure and hepatitis virus infection to HCC risk, we conducted a nested case-control study using sera stored before HCC diagnosis in the longitudinal cohort of atomic bomb survivors. The study included 224 HCC cases and 644 controls that were matched to the cases on gender, age, city, and time and method of serum storage, and countermatched on radiation dose. The cumulative incidence of HCC by follow-up time and age increased significantly with radiation dose. The relative risk (RR) of HCC for radiation at 1 Gy was 1.67 (95% confidence interval: 1.22-2.35) with adjustment for alcohol consumption, body mass index (BMI), and smoking habit, whereas the RRs for HBV or HCV infection alone were 63 (20-241) and 83 (36-231) with such adjustment, respectively. Those estimates changed little when radiation and hepatitis virus infection were fit simultaneously. The RR of non-B, non-C HCC at 1 Gy was 1.90 (1.02-3.92) without adjustment for alcohol consumption, BMI, or smoking habit and 2.74 (1.26-7.04) with such adjustment.

CONCLUSION

These results indicate that radiation exposure and HBV and HCV infection are associated independently with increased HCC risk. In particular, radiation exposure was a significant risk factor for non-B, non-C HCC with no apparent confounding by alcohol consumption, BMI, or smoking habit.

Diabetes and pancreatic cancer: chicken or egg?

OBJECTIVES

Although half of all patients with pancreatic cancer are diabetic at the time of diagnosis, it remains unclear whether the diabetes associated with pancreatic cancer is a cause or an effect of the malignancy.

METHODS

Epidemiologic studies were reviewed, the geographic prevalence of diabetes and the incidence of pancreatic cancer were examined, and clinical and laboratory studies were reviewed.

RESULTS

Long-standing diabetes increases the risk of pancreatic cancer by 40% to 100%, and recent-onset diabetes is associated with a 4- to 7-fold increase in risk, such that 1% to 2% of patients with recent-onset diabetes will develop pancreatic cancer within 3 years. Treatment of diabetes or morbid obesity decreases the risk of pancreatic cancer, and metformin therapy decreases the risk due to both its antidiabetic and antineoplastic effects. Recent-onset diabetes associated with pancreatic cancer likely represents secondary or type 3 diabetes. The discrimination of type 3 diabetes from the more prevalent type 2 diabetes may identify the high-risk subgroup of diabetic patients in whom potentially curable pancreatic cancer may be found.

CONCLUSIONS

Type 2 and type 1 diabetes mellitus increase the risk of pancreatic cancer with a latency period of more than 5 years. Type 3 diabetes mellitus is an effect, and therefore a harbinger, of pancreatic cancer in at least 30% of patients.

Diabetes mellitus and risk of pancreatic cancer: A meta-analysis of cohort studies

BACKGROUND

Diabetes mellitus (DM) is widely considered to be associated with risk of pancreatic cancer (PaC), however, whether DM is a cause or a consequence of PaC is still controversial. We examined this association by conducting a detailed meta-analysis of cohort studies.

METHODS

Studies were identified by searching Medline and Embase through November 30, 2010. Summary relative risks (RRs) with their corresponding 95% confidence intervals (CIs) were calculated using a random-effects model.

RESULTS

A total of thirty-five cohort studies were included in this meta-analysis. DM was associated with an increased risk of PaC (the summary RRs=1.94; 95% CI, 1.66-2.27), with significant evidence of heterogeneity among these studies (p<0.001, I²=93.6%). Subgroup analyses revealed that the increased risk of PaC was independent of geographic locations, sex, study design, alcohol consumption, body mass index (BMI) and smoking status. In addition, the relative risk of PaC was correlated negatively with the duration of DM, with the highest risk of PaC found among patients diagnosed within less than 1 year. There was no significant publication bias (p=0.136 for Egger's regression asymmetry test).

CONCLUSIONS

Findings from this meta-analysis strongly support that diabetes is associated with an increased risk of PaC in both males and females and that DM is both an early manifestation and an etiologic factor of pancreatic cancer.

Glucose metabolism disorders and the risk of cancer

Diabetes and cancer are diseases which take the size of an epidemic spread across the globe. Those diseases are influenced by many factors, both genetic and environmental. Precise knowledge of the complex relationships and interactions between these two conditions is of great importance for their prevention and treatment. Many epidemiological studies have shown that certain types of cancer, especially gastrointestinal cancers (pancreas, liver, colon) and also the urinary and reproductive system cancers in women are more common in patients with diabetes or related metabolic disorders. There are also studies showing the inverse relationship between diabetes and cancer, or the lack of it, but they are less numerous and relate mainly to prostate cancer or squamous cell carcinoma of the esophagus. Epidemiological studies, however, do not say anything about the mechanisms of these dependencies. For this purpose, molecular research is needed on the metabolism of cells (including tumor cells) and on metabolic dysfunctions that arise due to changes in the cell environment taking place in the sick, as well as in the intensely treated human organism.

Obesity, type 2 diabetes and risk of digestive cancer

The frequency of obesity has been increasing worldwide for 20 years. Many epidemiological studies support a correlation between obesity and increased risk of cancer, particularly digestive cancers in both genders, and gynaecological cancer in women. Currently, about 5% of cancers could be directly related to overweight. Carcinogenesis mechanisms induced by obesity involve insulin resistance, adipokine and angiogenic factor secretions, and inflammation. Experimental and clinical evidence suggest that insulin resistance plays a major role in carcinogenesis. Insulin and non-protein banded IGF-1, whose levels are increased in type 2 diabetes, stimulate cellular growth and inhibit apoptosis. Abnormalities in adipokine secretion by the central adipose tissue play a role at different stages of obesity-induced carcinogenesis. Excess of leptin and PAI-1, associated with a decrease in adiponectin secretion in obese people, contributes to carcinogenesis through cellular growth and angiogenesis stimulation. Remodelling of the extracellular matrix due to metalloproteinase stimulation by PAI-1 is also able to promote cell migration. Obesity not only increases cancer frequency, but is also liable to modify the prognosis and the response to antiangiogenic therapy of digestive cancers. This data suggests the need for clinicians to take into account overweight in cancer risk evaluation and to consider obesity and metabolic disorders as confounding factors in designing therapeutic studies.

Diabetes mellitus and increased risk of biliary tract cancer: systematic review and meta-analysis

OBJECTIVE

Epidemiological evidences indicate that diabetic individuals may have an increased risk of several cancers; however, the relationships between diabetes and risk of cancers of biliary tract or its subsites remain unclear.

METHODS

To provide a quantitative assessment of this relationship, we identified studies by a literature search of Medline (from 1 January 1966) and EMBASE (from 1 January 1974), through 31 July 2010, and by searching the reference lists of pertinent articles. Summary relative risks with corresponding 95% confidence intervals were calculated with a random-effect model.

RESULTS

Analysis of 21 studies (8 case-control and 13 cohort studies) found that diabetes was associated with an increased risk of biliary tract cancer, compared with no diabetes (summary RRs = 1.43, 95% CI = 1.18-1.72), with significant heterogeneity among studies (p = 0.001). The positive association was also found between diabetes and risk of gallbladder cancer or extrahepatic cholangiocarcinoma, but not cancer of ampulla of Vater. No significant publication bias was found.

CONCLUSION

These findings strongly support the link between diabetes and increased risk of cancer of biliary tract and its subsites: gallbladder cancer or extrahepatic cholangiocarcinoma, but not cancer of ampulla of Vater.

Prospective study of self-reported diabetes and risk of upper gastrointestinal cancers

BACKGROUND

Although gastric noncardia adenocarcinoma (GNCA) incidence rates in the United States have decreased, the rates of gastric cardia adenocarcinoma (GCA) and esophageal adenocarcinoma (EADC) have increased. Obesity increases the risks of GCA and EADC, and the associations may be partially mediated by insulin resistance. A few case-control studies have shown an association between diabetes and an increased risk of EADC.

METHODS

We prospectively examined the association between diabetes and upper gastrointestinal (UGI) cancers in a cohort of 469,448 people in the United States, ages 50 to 71 at baseline. Cox proportional hazards regression was used to estimate the HR and 95% CI for diabetes and UGI cancers, controlling for multiple potential confounders, including body mass index (BMI).

RESULTS

We observed no association of self-reported diabetes with risk of EADC, HR (95% CI) = 0.98 (0.73-1.31), esophageal squamous cell carcinoma (ESCC), HR (95% CI) = 1.02 (0.60-1.74), or GNCA, HR (95% CI) = 0.98 (0.70-1.37). However, diabetes was significantly associated with an increased risk of GCA, HR (95% CI) = 1.89 (1.43-2.50). The significant association between diabetes and risk of GCA remained after adjustment for BMI, HR (95% CI) = 1.70 (1.28-2.26) and did not differ by BMI strata (P(interaction) = 0.83). The significant association was unchanged when restricting to only overweight subjects (BMI 25 to ≤30), HR (95% CI) = 1.83 (1.18-2.85).

CONCLUSIONS

We found a significant association between self-reported diabetes and increased risk of GCA.

IMPACT

Our results suggest that the metabolic and hormonal changes related to diabetes may play a role in the etiology of GCA independently from BMI.

Type 2 diabetes does not worsen prognosis in hepatocellular carcinoma

INTRODUCTION

Type 2 diabetes (T2DM) is associated with liver inflammation and carcinogenesis. The prevalence of T2DM among patients with liver cirrhosis and hepatocellular carcinoma is increasing. However, the effect of T2DM on the natural history of hepatocellular carcinoma is not known.

AIM

To examine the effect of T2DM on hepatocellular carcinoma (HCC) survival in treated and untreated disease.

METHODS

Retrospective analysis was performed on HCC cases diagnosed during 2000-2005, and prospectively during 2006-August 2007. Demographics, HCC staging, response to treatment, and survival were collected. A comparison was made between patients with T2DM and without T2DM.

RESULTS

One hundred and thirty-five patients were recruited in total; 58 (43%) had T2DM. Seventy (37 diabetic) patients were treated with percutaneous radiological therapies, with 168 treatments given. Treatment was determined by AASLD guidelines and patient tolerance, there was no randomisation. There was no significant difference in survival between diabetic and nondiabetic patients. There was a nonsignificant trend towards greater survival in diabetic patients (overall median survival diabetics 21 mths vs nondiabetics 5 mths, P=0.355).

CONCLUSIONS

T2DM does not negatively impact on the natural history of treated or untreated HCC.

Risk of cancer in a large cohort of U.S. veterans with diabetes

Prior studies of cancer risk among diabetic men have reported inconsistent findings. The aim of this study was to assess the risk of cancer among a large cohort (n = 4,501,578) of black and white U.S. veterans admitted to Veterans Affairs hospitals. The cancer risk among men with diabetes (n = 594,815) was compared to the risk among men without diabetes (n = 3,906,763). Poisson regression was used to estimate adjusted relative risks (RRs) and 95% confidence intervals (CIs). Overall, men with diabetes had a significantly lower risk of cancer (RR = 0.93, 95%CI = 0.93-0.94). Men with diabetes, however, had increased risks of cancers of the liver (RR = 1.95, 95%CI = 1.82-2.09), pancreas (RR = 1.50, 95%CI = 1.42-1.59), biliary tract (RR = 1.41, 95%CI = 1.22-1.62), colon (RR = 1.20, 95%CI = 1.16-1.25), rectum (RR = 1.12, 95%CI = 1.07-1.18), and kidney (RR = 1.09, 95%CI = 1.03-1.16), as well as leukemia (RR = 1.14, 95%CI = 1.08-1.21) and melanoma (RR = 1.13, 95%CI = 1.03-1.24). In contrast, men with diabetes had decreased risks of cancers of the prostate (RR = 0.89, 95%CI = 0.87-0.91), brain (RR = 0.91, 95% CI = 0.82-0.99), buccal cavity (RR = 0.85, 95%CI = 0.82-0.89), lung (RR = 0.79, 95%CI = 0.77-0.80), esophagus (RR = 0.77, 95%CI = 0.72-0.82), and larynx (RR = 0.76, 95%CI = 0.71-0.80). These findings indicate that black and white men with diabetes are at significantly lower risk of total cancer and of two of the most common cancers among U.S. males; lung and prostate cancers. These decreased risks were offset, however, by increased risks of cancer at several sites. Hyperinsulinemia may explain the increased risks of the digestive cancers, while lower testosterone levels, in the case of prostate cancer, and higher BMI, in the case of lung cancer, may explain the decreased risks of those tumors.

Nonalcoholic fatty liver disease and nonalcoholic steatohepatitis in Japan

During the past 20 to 30 years, the frequency of patients presenting with nonalcoholic fatty liver diseases (NAFLD) has increased gradually in Japan in proportion to the increase in the population with life-style related diseases. We describe here the current status of the clinical and basic aspects of research into NAFLD in Japan. The increase in the incidence of life-style-related diseases has resulted in an increase in NAFLD throughout the past 20 to 30 years. The rate of obesity in the population is not high compared to western countries but the incidence of NAFLD is similar to those countries. In 2008 we started a nationwide study of NAFLD which has been supported by the Ministry of Labor and Welfare Japan. In this project, we planned to investigate the epidemiology, genetic backgrounds and biochemical markers, and liver injury in patients with diabetes mellitus (DM) and hepatocellular carcinoma in NASH, and treatment of NASH. Approximately 20 to 25% of DM patients showed NAFLD in which the prevalence of NASH might be more than 30 to 40%. Fortunately, we have been able to obtain very interesting results from our group studies, including single necleotide polymorphisms (SNPs) which will be published in the near future.

Intensive glycaemic control and cancer risk in type 2 diabetes: a meta-analysis of major trials

AIMS/HYPOTHESIS

The purpose of this study was to explore the relationship between hyperglycaemia in type 2 diabetes and risk of cancer incidence or cancer mortality. We were interested to determine if data from major randomised controlled trials would support a hypothesis that improving glycaemic control may reduce the risk of cancer outcomes.

METHODS

We included major randomised controlled trials conducted with an overall aim of intensified glycaemic control in type 2 diabetes. We abstracted data from published papers and supplemental material and conducted separate meta-analyses of cancer mortality and cancer incidence.

RESULTS

Four trials reported cancer mortality for the intensive (222 events in 53,892 person-years) and standard control (155 events in 38,743 person-years) arms (UK Prospective Diabetes Study [UKPDS] 33, UKPDS 34, Action to Control Cardiovascular Risk in Diabetes [ACCORD] and Veterans Affairs Diabetes Trial [VADT]); the summary risk ratio for cancer mortality was 1.00 (95% CI 0.81-1.24; I² = 0%). Excluding the UKPDS metformin trial resulted in a pooled risk estimate of 1.03 (95% CI 0.83-1.29; I² = 0%). Three trials reported cancer incidence for the study arms (Action in Diabetes and Vascular Disease: Preterax and Diamicron MR Controlled Evaluation [ADVANCE], PROspective pioglitAzone Clinical Trial In macroVascular Events [PROactive], Rosiglitazone Evaluated for Cardiac Outcomes and Regulation of Glycaemia in Diabetes [RECORD]) with 357 events in 47,974 person-years with improved glycaemic control and 380 events in 45,009 person-years in the control arms; the pooled risk ratio for cancer incidence was 0.91 (95% CI 0.79-1.05; I² = 0%).

CONCLUSIONS/INTERPRETATION

Data from large randomised controlled trials of intensified glycaemic control suggest that cancer risk is not reduced by improving glycaemic control in type 2 diabetes. These data therefore do not support the hypothesis that hyperglycaemia is causally linked to increased cancer risk.

Prevalence of type 2 diabetes mellitus in Japanese patients with hepatocellular carcinoma

The possibility has been raised in a number of cohort and case-control studies that diabetes mellitus (DM) may increase the risk of liver cancer, as well as that of cancer at other sites. To verify this possibility, we conducted a retrospective cohort study to determine the prevalence of type 2 DM in Japanese patients with hepatocellular carcinoma (HCC). A total of 1,251 patients with HCC, diagnosed at two major liver centers in the Nagasaki area, were consecutively recruited and categorized according to the etiology of HCC into four groups: HCC-B, HCC-C, HCC-BC and HCC-nonBC cases. Type 2 DM was diagnosed on the basis of standard criteria. The prevalence rate of HCC-nonBC and HCC-C was significantly higher than that of HCC-B, while the prevalence rate of HCC-nonBC was significantly higher than that of HCC-C. The prevalence of type 2 DM in HCC-B, HCC-C and HCC-nonBC patients under 66 years of age was 11, 31 and 32%, respectively, vs. 24, 22 and 40%, respectively, in patients over 66 years of age. In patients over 66 years of age, the prevalence of type 2 DM in HCC-B and HCC-nonBC cases was increased, whereas the prevalence of type 2 DM in HCC-C cases was significantly decreased. Our findings indicate that the effects of the interaction between type 2 DM and HCV increase the prevalence of HCC.

Diabetes and cancer

Diabetes and cancer are common conditions, and their co-diagnosis in the same individual is not infrequent. A link between the two conditions has been postulated for almost 80 years, but only in the past decade has significant epidemiological evidence been amassed to suggest that diabetes and cancer are associated, and the link appears causal. Hyperinsulinaemia, adipocytokines, growth factors and epigenetic changes may be implicated in the pathogenesis of cancer amongst patients with diabetes, and recently, diabetes therapies have also been implicated. There is reasonable circumstantial evidence that metformin may decrease the risk of cancer amongst diabetic patients. Much more research is required to elucidate the link between diabetes and cancer, particularly the potential link with diabetes treatments.

Prevalence and recurrence rate of colonic lesions in acromegalic patients

Acromegaly is associated with an increased prevalence of colonic polyps. The aim of this study was to evaluate the prevalence and recurrence rate of colonic polyps in acromegalic patients. Ninety-six acromegalic patients and 100 irritable bowel syndrome patients (IBS) were enrolled in the study. Twenty patients who were cured exclusively by surgery, and 20 patients that could not be hormonally controlled were re-examined colonoscopically after 36 months. Twenty-nine of 96 acromegalic patients (30.2%) had colonic polyps. In the IBS group, 10 (10.0%) had colonic polyps. The prevalence of colonic polyps was significantly higher in acromegaly. The group of acromegalic patients with and without polyps did not differ significantly with regard to plasma GH, IGF-I, fasting insulin levels and glycemic status. The presence of colonic polyps was correlated with increased patient age and male gender. We did not observe a difference in terms of polyp recurrence frequencies in the patients cured by surgery compared to uncontrolled patients. Acromegalic patients have a higher prevalence of colonic polyps than that of control subjects. We could not identify any factors that could predict polyps within the acromegalic patients - but age and male sex.

Use of sulphonylurea and cancer in type 2 diabetes-The Hong Kong Diabetes Registry

BACKGROUND

Hyperglycaemia is a risk factor for cancer and some sulphonylureas have anti-oxidant properties. This study examined associations between use of sulphonylureas and cancer.

METHODS

A consecutive cohort of 6103 Hong Kong Chinese patients with T2DM, free of cancer, was analysed using Cox models. Sulphonylurea usage was defined as use of the drugs at or within 2.5 years before enrolment and/or during follow-up periods. We adjusted for identified risk factors of cancer, use of other drugs, non-linear associations of lipids with cancer and probabilities of use of these drugs at different times and doses where appropriate.

RESULTS

During a median of 4.91 years of follow-up, 271 developed cancer. Glibenclamide, gliclazide and glipizide were ever used in 32.5% (n = 1983), 47.8% (n = 2920) and 13.5% (n = 823). After adjustment for covariates, use of gliclazide and glibenclamide was associated with reduced cancer risk in a dose-dependent manner. In addition, there were interactions between metformin and glibenclamide/glipizide use towards lower adjusted cancer risks.

CONCLUSIONS

In T2DM, use of glibenclamide and gliclazide may be associated with reduced cancer risk.

Insulin resistance and hepatocarcinogenesis

Hepatocellular carcinoma (HCC) accounts for 85-90% of liver cancers and is one of the most frequent carcinomas in the world. HCCs classically develop against the background of chronic liver diseases. Common causes of such liver diseases are viral hepatitis, alcoholic hepatitis, or immune-related diseases; however, 15-50% of patients with HCCs have none of these classic antecedents, especially in developed countries. In this context, obesity and diabetes mellitus have been found to exhibit an increased risk of HCC. Both conditions are associated with insulin resistance. The tumorigenic effects of insulin resistance and complementary hyperinsulinemia could be mediated directly by insulin signaling, or indirectly related to changes in endogeneous hormone metabolism, particularly insulin-like growth factor I. Conversely, insulin resistance may be a consequence of obesity and hepatic inflammation, both of which can themselves promote tumorigenesis, mainly through cytokine production and/or generation of oxidative stress. Because the prevalence of obesity is now increasing throughout the world, insulin resistance is sure to be emphasized as a major factor in hepatocarcinogenesis in the foreseeable future.

Diabetes and risk of bladder cancer: evidence from a case-control study in New England

BACKGROUND

Diabetes is an emerging public health issue in the US, affecting 11% of Americans over the age of 20, with long-term complications that include cardiovascular disease, retinopathy, neuropathy, and nephropathy. A recent meta-analysis found that bladder cancer incidence was approximately 40% higher in individuals with diabetes; however, few studies considered duration or type of therapy and had limited adjustment for potentially confounding factors.

METHODS

To further investigate the potential role of diabetes in risk of bladder cancer, the authors analyzed data from a case-control study conducted in New Hampshire in which patients with bladder cancer, and controls sampled from the population, completed an interview regarding history of diabetes, cigarette smoking history, height, weight, and history of urinary tract infections.

RESULTS

The study consisted of 331 cases and 263 controls on whom information regarding diabetes was ascertained. History of diabetes was related to an increased bladder cancer risk (adjusted odds ratio = 2.2, 95% CI, 1.3 to 3.8). The association was strongest in those who had diabetes for the longest duration (OR for 16 or more years = 3.6, 1.1 to 11.2) and in those taking oral hypoglycemic medications (OR = 3.3, 1.5 to 7.1).

CONCLUSIONS

Our findings support an association between bladder cancer incidence and diabetes, and further suggest that the risk may be greater among patients taking oral hypoglycemics and those with diabetes of longer duration.

Diabetes mellitus, hyperglycaemia and cancer

A moderate increase in cancer risk has been shown in diabetic patients and in individuals with abnormal glucose tolerance, mainly for digestive sites, independently of obesity, with in contrast, a protective effect for prostate cancer. Insulin-resistance with compensatory hyperinsulinemia, and elevated levels of circulating growth factors are usually considered to be the link between cancer and hyperglycaemia, through activated cell proliferation. Treatments inducing elevated plasma insulin seem to increase cancer risk but insulin-sensitizers (metformine, thiazolidinediones) seem to reduce cancer risk. In 2009, there was a controversy on the specific action of glargine insulin to increase cancer risk, from an observational study in Germany, which accumulated a number of methodological pitfalls. There was no confirmation of these results in the three other European studies commissioned by Diabetologia, to validate or to refute the results. The recent interest for cancer in the diabetes community should not distract from appropriate management of diabetic patients to prevent cardiovascular diseases, as the risk for death from macrovascular complications is higher than death from cancer in type 2 diabetic patients. Greater public awareness about healthy lifestyles (diet, physical activity) is needed at the general population level to prevent these two major increasing public health issues, diabetes and cancer, as well as obesity, a risk factor for both of these diseases.

Promoting Effects of Streptozotocin-induced Diabetes on Induction of Hepatic Preneoplastic Lesions by Diethylnitrosamine in Rats

The effects of streptozotocin (STZ)-induced diabetes on induction of hepatic preneoplastic lesions by diethylnitrosamine (DEN) were investigated in male Fischer rats. A single dose of STZ was injected intravenously either 2 weeks before or after initiation with DEN. The blood glucose levels were significantly elevated from 1 week after STZ-injection until autopsy. The numbers of GST-P positive foci at 1 week after DEN administration in the STZ-injected rats were similar to those in the non-diabetic rats. In contrast, both the numbers and areas of GST-P positive foci > 2 mm in diameter 8 weeks after DEN administration were increased significantly in the rats treated with STZ after DEN exposure compared with the non-diabetic control rats. The results suggest that hepatic preneoplastic lesions initiated with DEN are promoted by STZ treatment-inducing diabetes.

Prospective study reveals associations between colorectal cancer and type 2 diabetes mellitus or insulin use in men

BACKGROUND & AIMS

Type 2 diabetes mellitus (DM) is associated with an increased risk of colorectal cancer (CRC); it is not clear if this association varies by sex or other factors. Insulin use might also be associated with CRC risk. We investigated associations of type 2 DM and insulin use with CRC risk.

METHODS

The Cancer Prevention Study II Nutrition Cohort is a prospective study of cancer incidence. In 1992 or 1993, adult participants (n = 184,194) completed a detailed, self-administered questionnaire. Follow-up questionnaires were sent in 1997 and every 2 years thereafter. Cox proportional hazards regression analysis was used to calculate relative risks (RR) and 95% confidence intervals (CI), adjusting for covariates.

RESULTS

After exclusions, 73,312 men and 81,663 women remained in the final analytic cohort; 1567 men (227 with type 2 DM) and 1242 women (108 with type 2 DM) were diagnosed with colon or rectal cancer by 2007. Among men, type 2 DM was associated with increased risk of incident CRC compared to not having type 2 DM (RR: 1.24; 95% CI: 1.08-1.44); risk was higher for participants with type 2 DM using insulin (RR: 1.36; 95% CI: 1.05-1.78), and participants with type 2 DM not using insulin (RR: 1.22, 95% CI: 1.04-1.45). Among women, type 2 DM and insulin use were not associated with risk of incident CRC (RR: 1.01; 95% CI: 0.82-1.23 and RR: 0.95; 95% CI: 0.64-1.41, respectively).

CONCLUSIONS

There is a modest association between type 2 DM and CRC among men, but not women. Insulin use is not associated with a substantially increased risk of CRC.

Body mass index as a predictor of colorectal neoplasia in ethnically diverse screening population

BACKGROUND

Recent guidelines from the American College of Gastroenterology for screening for colorectal cancer have included obesity as an important risk factor. The recommendation for screening obese people at earlier age was tempered by the need for more data regarding obesity and colorectal neoplasia.

AIMS

We designed a cross-sectional study to further examine the predictive value of obesity for colorectal adenomas in asymptomatic patients.

METHODS

We prospectively collected demographic, medical, lifestyle, and dietary history from asymptomatic patients presenting for screening colonoscopy. Patients underwent complete colonoscopy using high-definition colonoscope to detect colorectal adenomas. We defined advanced neoplasia as large (≥ 1 cm) adenoma, villous adenoma, high-grade dysplasia or cancer.

RESULTS

Six hundred patients with median age of 56 years completed the study. Over 40% of these patients did not consider themselves Caucasian, and less than 5% had a first-degree relative with colorectal cancer. Overall, 40 patients (6.7%) had advanced neoplasia and 216 (36.3%) had any adenoma. There were 185 obese patients (30.8%), who had a prevalence of 44.3% for any adenoma and 13.0% for advanced neoplasia. After multivariate analysis, obesity [body mass index (BMI) ≥ 30 kg/m(2)] was significantly associated with increased risk of advanced neoplasia [odds ratio (OR) = 3.83; 95% confidence interval (CI): 1.94-7.55].

CONCLUSIONS

Obesity was associated with advanced neoplasia in this screening population. Our data regarding the association of colorectal neoplasia with this modifiable risk factor has implications for screening and prevention of colorectal cancer.

Diabetes enhances hepatocarcinogenesis in noncirrhotic, interferon-treated hepatitis C patients

BACKGROUND

This retrospective cohort study assessed the impact of diabetes mellitus on hepatocarcinogenesis and determined the predictors of hepatocarcinogenesis in noncirrhotic, interferon-treated patients with hepatitis C virus infection.

METHODS

A total of 2058 hepatitis C virus-positive, noncirrhotic patients treated with interferon were enrolled. The median follow-up period was 6.7 years. The primary end point was the onset of hepatocellular carcinoma. The cumulative rate of new hepatocellular carcinoma cases was computed by the Kaplan-Meier method and Cox proportional hazard analysis according to diabetic state and response to interferon therapy.

RESULTS

The cumulative rates of hepatocellular carcinoma in diabetic patients (3.2% at 4 years, 8.5% at 8 years, and 24.4% at 12 years) were significantly higher than those of nondiabetic patients (1.3% at 4 years, 2.2% at 8 years, and 5.6% at 12 years, P<.001). In patients with a sustained virologic response, diabetes had no significant effect on the rate of hepatocarcinogenesis. In contrast, the rate in patients with a nonsustained virologic response was significantly higher in diabetic than in nondiabetic patients. Multivariate analysis identified lack of sustained virologic response (hazard ratio [HR] 7.28; 95% confidence interval [CI], 3.28-16.15; P<.001) and diabetes as independent risk factors for hepatocarcinogenesis (HR 2.00; 95% CI, 1.05-3.84; P=.036).

CONCLUSIONS

Our results highlight the enhancing effect of diabetes mellitus on hepatocarcinogenesis in noncirrhotic, interferon-treated patients with hepatitis C virus. The sustained virologic response induced by interferon therapy eliminates the influence of diabetes and markedly reduces the rate of hepatocarcinogenesis in such patients.

Substantially increased risk of cancer in patients with diabetes mellitus: a systematic review and meta-analysis of epidemiologic evidence in Japan

AIMS

Several meta-analyses have shown that diabetes mellitus affects the risk of certain site-specific cancers. However, a meta-analysis on the overall risk of cancer has not yet been performed.

METHODS

We performed a search of MEDLINE and the Cochrane Library for pertinent articles (including their references) that had been published as of June 10, 2010. English-language, original observational cohort studies and case-control studies conducted in Japan were included for a qualitative review and a meta-analysis.

RESULTS

A total of 22,485 cancer cases were reported in four cohort studies and one case-control study (with a total of 250,479 subjects). With these five reports, a meta-analysis of the all-cancer risk in both men and women showed an increased risk in subjects with diabetes, compared with nondiabetic subjects (OR 1.70, 95% CI 1.38-2.10). The increase in the risk ratio adjusted for possible confounders was significant in men and borderline in women (adjusted RR 1.25, 95% CI 1.06-1.46 in men; adjusted RR 1.23, 95% CI 0.97-1.56 in women). An analysis of site-specific cancers revealed increased risks for incident hepatocellular cancer (OR 3.64, 95% CI 2.61-5.07) and endometrial cancer (OR 3.43, 95% CI 1.53-7.72).

CONCLUSIONS

As is the case in Western countries, Asian people with diabetes have a higher risk of incident cancer than those without diabetes. Cancer prevention and early detection should be important components of diabetes management in light of the exponentially increasing prevalence of diabetes, which has substantial implications in public health and clinical practices.

Epidemiology and risk factors for kidney cancer

After more than two decades of rising rates, in recent years the total kidney cancer incidence worldwide has shown signs of stabilizing, or even decreasing. In adults, kidney cancer consists of renal cell carcinoma (RCC), the predominant form, and renal transitional cell carcinoma (RTCC); these types primarily arise in the renal parenchyma and renal pelvis, respectively. Although temporal trends by kidney cancer type are not well established worldwide, incidence of RCC in the US has continued to rise, mainly for early-stage tumors, while that of RTCC has declined, and total kidney cancer mortality rates have leveled. Stabilization of kidney cancer mortality rates has also been reported in Europe. These trends are consistent with reports of increasing incidental diagnoses and a downward shift in tumor stage and size in clinical series. The changing prevalence of known risk factors for RCC, including cigarette smoking, obesity, and hypertension, is also likely to affect incidence trends, although their relative impact may differ between populations. Accumulating evidence suggests an etiologic role in RCC for physical activity, alcohol consumption, occupational exposure to trichloroethylene, and high parity among women, but further research is needed into the potential causal effects of these factors. Genetic factors and their interaction with environmental exposures are believed to influence risk of developing RCC, but a limited number of studies using candidate-gene approaches have not produced conclusive results. Large consortium efforts employing genome-wide scanning technology are underway, which hold promise for novel discoveries in renal carcinogenesis.

Associations of diabetes mellitus with site-specific cancer mortality in the Asia-Pacific region

BACKGROUND

Owing to the increasing prevalence of obesity and diabetes in Asia, and the paucity of studies, we examined the influence of raised blood glucose and diabetes on cancer mortality risk.

MATERIALS AND METHODS

Thirty-six cohort Asian and Australasian studies provided 367, 361 participants (74% from Asia); 6% had diabetes at baseline. Associations between diabetes and site-specific cancer mortality were estimated using time-dependent Cox models, stratified by study and sex, and adjusted for age.

RESULTS

During a median follow-up of 4.0 years, there were 5992 deaths due to cancer (74% Asian; 41% female). Participants with diabetes had 23% greater risk of mortality from all-cause cancer compared with those without: hazard ratio (HR) 1.23 [95% confidence interval (CI) 1.12, 1.35]. Diabetes was associated with mortality due to cancer of the liver (HR 1.51; 95% CI 1.19, 1.91), pancreas (HR 1.78; 95% CI 1.20, 2.65), and, less strongly, colorectum (HR 1.32; 95% CI 0.98, 1.78). There was no evidence of sex- or region-specific differences in these associations. The population attributable fractions for cancer mortality due to diabetes were generally higher for Asia compared with non-Asian populations.

CONCLUSION

Diabetes is associated with increased mortality from selected cancers in Asian and non-Asian populations.

Diabetes and risk of incident colorectal cancer in a prospective cohort of women

OBJECTIVE

To determine whether accounting for the time dynamics of diabetes exposure will change the risk estimates for colorectal cancer.

METHODS

We analyzed data from the 45, 516 women enrolled in the BCDDP follow-up cohort study. We used proportional hazards regression to obtain multivariable-adjusted risk estimates for incident colorectal cancer for prevalent diabetes at baseline and diabetes as a time-dependent variable.

RESULTS

Subjects with diabetes had a statistically significant increased risk of colorectal cancer compared to subjects without diabetes (RR = 1.60, 95% CI 1.18-2.18). When we defined exposure as duration of diabetes exposure at cohort exit, we found that in the first 4 years after diagnosis risk was essentially the same as in those never having had a diagnosis of diabetes. For those who had been diagnosed between 4 and 8 years previously, however, we observed a RR of 2.36 (95% CI 0.96-5.79), while longer duration of exposure was associated with smaller and then no change in risk compared to those without a diagnosis of diabetes.

CONCLUSIONS

These results are consistent with the theory that hyperinsulinemia can explain, at least in part, the association of diabetes with colorectal cancer, but in a time-dependent manner.

Relationships between diabetes and medical and dental care costs: findings from a worksite cohort study in Japan

The purpose of this study was to evaluate the relationships between diabetes and medical and dental care costs from a 5-yr prospective observation of Japanese workers. The data were derived from health and dental examinations and health insurance claims of 4,086 workers aged 40-54 yr. At baseline, the subjects were assigned to four categories: known diabetes; undiagnosed diabetes; impaired fasting glucose (IFG); and non-diabetic. The differences in health care costs among the non-diabetics, IFG and undiagnosed diabetes groups were not seen at baseline, but the costs incurred by the subjects with undiagnosed diabetes substantially increased thereafter. Over 5 yr of the study period, compared with the non-diabetic group, subjects with known diabetes incurred 3.9- and 2.9-fold higher annual inpatient and outpatient costs, respectively, while subjects in the undiagnosed diabetes group incurred 3.0- and 1.6-fold higher costs, respectively. There were no significant associations between annual dental care costs and diabetic status. The excess costs of medical care among subjects with diabetes were attributable to diabetes itself, heart disease and cerebrovascular disease, but not cancer. Among middle-aged workers, diabetics incurred significantly greater medical care costs than non-diabetics, whereas IFG was not associated with higher costs.

Enhanced tumorigenesis of forestomach tumors induced by N-Methyl-N'-nitro-N-nitrosoguanidine in rats with hypoinsulinemic diabetes

Hyperinsulinemia and hyperglycemia in prediabetic and diabetic patients are thought to increase the risk of developing neoplasms because insulin is a growth factor with pre-eminent metabolic but also mitogenic effects. To determine the effect of hypoinsulinemic diabetic conditions on carcinogenesis, we examined N-Methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced forestomach carcinogenesis in hypoinsulinemic diabetic WBN/Kob rats aged about 45 weeks (DM) compared with non-diabetic younger WBN/Kob rats (C1), non-diabetic Wistar rats age-matched to DM (C2), and non-diabetic Wistar rats age-matched to C1 (C3). All rats were treated with MNNG by gavage and were killed at 40 weeks after dosing. Various-sized tumors were disseminated throughout the forestomach of all rats, and the ratio of the area of tumors to the whole forestomach area was 23.3% in the DM group and was higher than in the C1-3 (4.2-14.3%) groups. The incidence of carcinoma was much higher in the DM group (36.8%) than in the C1-3 (7.1-16.7%) groups, and the incidence of papilloma was also significantly higher in the DM group (84.2%) than in the C1-3 (28.5-50.0%) groups. The average thickness of the squamous epithelium in the non-neoplastic mucosa was significantly greater in the DM group (50.8 mum) than in the C1-3 (29.6-37.9 microm) groups. Immunohistochemically, the Ki-67-positive index in the non-tumorous mucosa of the DM group (42.0%) was significantly higher than that of the C1-3 groups (18.8-33.3%). These results suggest that prolonged hyperglycemic conditions without hyperinsulinemia enhance tumorigenesis of MNNG-induced tumors by enhanced proliferative activity of the squamous epithelium in the rat forestomach.

Risk of malignant neoplasms of liver and biliary tract in diabetic patients with different age and sex stratifications

We prospectively investigated 615,532 diabetic patients and 614,871 age-matched and sex-matched control subjects selected from National Health Insurance claims for malignant neoplasms of liver and biliary tract (International Statistical Classification of Diseases and Related Health Problems, 9th edition, codes 155 and 156, respectively) between 2000 and 2006. The person-year approach with Poisson assumption was used to estimate the hazard rates. We also evaluated the age-specific and sex-specific relative risks of these two malignancies in relation to diabetes with Cox proportional hazard regression model with adjustment for potential confounders. The overall hazard rate of malignant neoplasm of the liver was 32.76 and 17.41 per 10,000 patient-years, respectively, for diabetic men and women; the corresponding figures for biliary tract neoplasm were much lower at 1.42 and 1.60 per 10,000 patient-years. Compared with control subjects, diabetic patients had a two-fold increased risk of malignant neoplasm of the liver, but this risk was attenuated by adjusting for selected clinical risk factors (hazard ratio [HR] 1.21; 95% confidence interval [CI] 1.17-1.25). Additionally, diabetic patients were associated with increased risk of biliary neoplasms with an approximate magnitude of 20%-30%, but the HR was attenuated and became insignificant after adjustment for clinical risk factors (HR 1.07; 95% CI 0.95-1.21). Diabetic patients with cirrhosis had the highest relative risk of liver neoplasm (HR 85.25; 95% CI 76.84-94.58), whereas those with cholangitis had the highest risk of biliary tract neoplasm (HR 70.30; 95% CI 51.95-95.12) compared with control subjects without any clinical risk factors.

CONCLUSION

This population-based study confirms the association of diabetes with liver neoplasm and suggests that diabetic patients with certain clinical risk factors should be educated for strict adherence of liver neoplasm screening.

Glycated hemoglobin and antidiabetic strategies as risk factors for hepatocellular carcinoma

AIM: To evaluate the relationship between glycemic control [assessed by glycated hemoglobin (HbA1c)], antidiabetic therapies and the risk of hepatocellular carcinoma (HCC).

METHODS: We recruited 465 patients with HCC, 618 cases with liver cirrhosis and 490 controls with no liver disease. Among subjects with type 2 diabetes mellitus (DM2), the associations between the antidiabetic strategies and HbA1c level with HCC were determined through 2 series of multivariate logistic regression models using cirrhotic patients and controls as comparison groups.

RESULTS: DM2 prevalence was 31.2% in patients with HCC, 23.2% in cirrhotic patients and 12.6% in controls (P < 0.0001). In 86% of study subjects, DM2 had been diagnosed for more than 1 year before the HCC diagnosis. HCC patients with DM2 had a 1.5-2.5-fold increased risk of liver cancer. The HbA1c mean levels were significantly higher in DM2 patients with HCC than in cirrhotic and control DM2 patients. Antidiabetic treatment with metformin was more common among cirrhotic and control DM2 subjects than among cases with HCC. In both series of multivariate analyses, treatment with metformin significantly reduced the risk of HCC by more than 80% compared with sulphonylureas and insulin therapy. No significant differences were seen between sulphonylureas and insulin treatment. Elevated HbA1c levels were positively related to the risk for HCC in diabetic patients, with a 26%-50% increase in risk for each 1% increase in HbA1c values.

CONCLUSION: In patients with preexisting DM2, the risk of HCC is positively associated with poor chronic glycemic control and significantly decreased by metformin therapy.

Epidemiological aspects of neoplasms in diabetes

Glucose metabolism represents a complex system, and several components of the regulatory metabolic pathways may induce abnormalities in cellular growth and regulation. The strongest evidence of an association between glucose metabolism alterations and cancer derives from cohort studies, showing increased cancer incidence and mortality in the presence of diabetes. In particular, several studies clearly indicate an association between type 2 diabetes and the risk of colorectal, pancreatic, and breast cancer. An increased risk of liver, gastric, and endometrial malignancies has also been suggested. Type 1 diabetes is associated with an elevated risk of female reproductive organs and gastric cancers. The risk of malignancies is also increased at earlier stages of glucose metabolism abnormalities, with a linear relationship between cancer risk and plasma insulin levels, usually elevated in the presence of metabolic syndrome or diabetes. The prevalence of diabetes and obesity is rapidly increasing worldwide; if these conditions are associated even with a small increase in the risk of cancer, this will translate into important consequences for public health.