Diabetes mellitus and the incidence and mortality of colorectal cancer: a meta-analysis of 24 cohort studies

Investigating the Effects of AL049796.1 Silencing in Inhibiting High Glucose-Induced Colorectal Cancer Progression

Patients with colorectal cancer (CRC) and diabetes share many risk factors. Despite a strong association between diabetes and CRC being widely studied and confirmed, further genetic research is needed. This study found higher AL049796.1 and TEA domain transcription factor 1 (TEAD1) levels (both mRNA and protein) in CRC tissues of diabetic patients compared with nondiabetics, but no significant difference in miR-200b-3p levels. A positive correlation between AL049796.1 and TEAD1 protein existed regardless of diabetes status, whereas miR-200b-3p was only negatively correlated with TEAD1 protein in nondiabetic CRC tissues. In vitro experiments have shown that high glucose (HG) treatment increased AL049796.1 in CRC cells, and AL049796.1 silencing reduced HG-induced proliferation, migration and invasion, as well as connective tissue growth factor, cysteine-rich angiogenic inducer 61, and epidermal growth factor receptor protein expression. Mechanistic investigations indicated that AL049796.1 could mitigate suppression of miR-200b-3p on TEAD1 posttranscriptionally by acting as a competitive binder. In vivo, subcutaneous CRC tumors in streptozotocin (STZ)-induced mice grew significantly faster; AL049796.1 silencing did not affect the growth of subcutaneous CRC tumors but significantly reduced that of STZ-induced mice. Our study suggests that AL049796.1 independently contributes to the risk of CRC in diabetic patients, highlighting its potential as both a therapeutic target and a novel biomarker for CRC among individuals with diabetes.

Nonmetallic N/C Nanozyme Performs Continuous Consumption of Glu for Inhibition of Colorectal Cancer Cells

Colorectal cancer (CRC) is the third leading cause of cancer-related mortality. 5-Fluorouracil (5-FU) is the first choice for treatment of CRC, but it cannot avoid the negative effects from local high glucose (Glu) in tumor. Recently, 5-FU therapy has been combined with other treatment modalities for CRC synergistic therapy. Although these combination therapy strategies are more effective in cancer therapy, the toxicity side effects to the liver and cause metabolic acidosis still exist. Herein, we report an emerging amorphous honeycomb-like nitrogen-doped carbon (N/C) nanozyme with nicotinamide adenine dinucleotide (NADH) oxidase and catalase (CAT) activity and cascade it with natural glucose dehydrogenase (GDH) to realize NAD⁺ regeneration and further hyperglycemia management. In this case, by the coupling of N/C nanozyme with natural GDH to form a N/C-GDH system, the electron transfer route can switch from Glu to a common but limited electron receptor, i.e., NAD⁺ to ubiquitous large amounts of oxygen, achieving the purpose of sustainable consumption of Glu under NAD⁺ circulation and regeneration, and importantly escaping the generation of toxic H₂O₂. The combination of the N/C-GDH system and 5-FU on CRC cells was investigated to assess their synergistic bioeffects. Notably, our results showed that the N/C-GDH system and 5-FU in combination significantly suppress the proliferation of human colon cancer cells (HCT-116) by reducing the sugar level and induced apoptosis compared with either material or drug used alone. This work expands the nanozymes in blood Glu management as well as the promising cancer cell inhibition and provides the possibility of nonmetallic nanomaterials in the realization of effective treatment of cancer.

Oxidatively Damaged Nucleic Acid: Linking Diabetes and Cancer

Significance: Our current knowledge of the mechanism between diabetes and cancer is limited. Oxidatively damaged nucleic acid is considered a critical factor to explore the connections between these two diseases. Recent Advances: The link between diabetes mellitus and cancer has attracted increasing attention in recent years. Emerging evidence supports that oxidatively damaged nucleic acid caused by an imbalance between reactive oxygen species generation and elimination is a bridge connecting diabetes and cancer. 8-Oxo-7,8-dihydro-2'-deoxyguanosine and 8-oxo-7,8-dihydroguanosine assume important roles as biomarkers in assessing the relationship between oxidatively damaged nucleic acid and cancer. Critical Issues: The consequences of diabetes are extensive and may lead to the occurrence of cancer by influencing a combination of factors. At present, there is no direct evidence that diabetes causes cancer by affecting a single factor. Furthermore, the difficulty in controlling variables and differences in detection methods lead to poor reliability and repeatability of results, and there are no clear cutoff values for biomarkers to indicate cancer risk. Future Directions: A better understanding of connections as well as mechanisms between diabetes and cancer is still needed. Both diabetes and cancer are currently intractable diseases. Further exploration of the specific mechanism of oxidatively damaged nucleic acid in the connection between diabetes and cancer is urgently needed. In the future, it is necessary to further take oxidatively damaged nucleic acid as an entry point to provide new ideas for the diagnosis and treatment of diabetes and cancer. Experimental drugs targeting the repair process of oxidatively generated damage require an extensive preclinical evaluation and could ultimately provide new treatment strategies for these diseases. Antioxid. Redox Signal. 37, 1153-1167.

Repurposing metformin for the treatment of gastrointestinal cancer

Diabetes mellitus type 2 and cancer share many risk factors. The pleiotropic insulin-dependent and insulin-independent effects of metformin might inhibit pathways that are frequently amplified in neoplastic tissue. Particularly, modulation of inflammation, metabolism, and cell cycle arrest are potential therapeutic cancer targets utilized by metformin to boost the anti-cancer effects of chemotherapy. Studies in vitro and in vivo models have demonstrated the potential of metformin as a chemo- and radiosensitizer, besides its chemopreventive and direct therapeutic activity in digestive system (DS) tumors. Hence, these aspects have been considered in many cancer clinical trials. Case-control and cohort studies and associated meta-analyses have evaluated DS cancer risk and metformin usage, especially in colorectal cancer, pancreatic cancer, and hepatocellular carcinoma. Most clinical studies have demonstrated the protective role of metformin in the risk for DS cancers and survival rates. On the other hand, the ability of metformin to enhance the actions of chemotherapy for gastric and biliary cancers is yet to be investigated. This article reviews the current findings on the anti-cancer mechanisms of metformin and its apparatus from pre-clinical and ongoing studies in DS malignancies.

Type 2 Diabetes Associated with Abnormal p53 Immunohistochemical Patterns in Colorectal Cancer

Abnormal p53 immunohistochemical pattern (p53-AP) including overexpression, complete absence and heterogeneity is surrogate of TP53 mutation. Using 742 cases of colorectal cancer (CRC), we show p53-AP is more common among type 2 diabetes (T2DM) patients than non-T2DM. Univariately, T2DM was significantly associated with p53-AP in overall patients, patients with microsatellite instability (MSI) stable/MSI-low phenotype or distal colorectal location. Furthermore, p53-AP was positively associated with lymph node metastasis and high TNM stage. Metformin treatment was negatively associated with p53-AP in T2DM patients. The results suggested T2DM might influence carcinogenesis, progression and prognosis via inducing TP53 mutation and abnormal p53 expression in CRC.

Glycemic control and the incidence of neoplasm in patients with type 2 diabetes: a meta-analysis of randomized controlled trials

PURPOSE

Previous epidemiologic studies indicate an increased risk of cancer and cancer mortality in patients with type 2 diabetes (T2D). Whether the resolution of hyperglycemia will lead to reduced risk of neoplasm in T2D remains uncertain. Therefore, we performed a meta-analysis to assess the association between glycemic control and incidence of neoplasm in T2D patients.

METHODS

Randomized controlled trials (RCTs) in T2D with significant HbA1c reduction difference between intensive/active and standard/control groups plus follow-up ≥48 weeks were included and analyzed by fixed-effect models, random-effect model, and meta-regression analysis accordingly.

RESULTS

Overall, 52 studies were included. Compared with standard/control treatment, intensive/active treatment led to significantly greater HbA1c reduction from baseline (WMD = -0.51%, 95% CI, -0.55 to -0.46%, P < 0.001), but was not associated with a decreased incidence of neoplasm (OR = 0.99, 95% CI, 0.94-1.03, I² = 2%) in T2D. Meta-regression analysis indicated that HbA1c reduction difference between intensive/active treatment and standard/control treatment was not associated with the incidence of neoplasm in T2D patients (β = -0.0011, 95% CI, -0.0058 to 0.0035, P = 0.625). In neoplasm-site subgroup analysis, a decreased incidence of breast neoplasm was observed in T2D patients using dipeptidyl-peptidase-4 inhibitor (OR = 0.56, 95% CI, 0.35-0.89, I² = 0%) and incidence of prostate neoplasm was reduced in T2D patients with glucagon-like peptide-1 receptor agonist treatment (OR = 0.66, 95% CI, 0.47-0.91, I² = 0%).

CONCLUSION

Improved glycemic control in short and medium periods achieved by existing glucose-lowering drugs or strategies may not confer reduced risk of neoplasm in patients with T2D. Studies with longer follow-up duration are needed to better elucidate the long-period effects.

Pre- and Post-diagnosis Diabetes as a Risk Factor for All-Cause and Cancer-Specific Mortality in Breast, Prostate, and Colorectal Cancer Survivors: a Prospective Cohort Study

Objective: The relationship between diabetes and all- and cause-specific mortality in individuals with common cancers (breast, colorectal, and prostate) remains both under-researched and poorly understood. Methods: Cancer survivors (N = 37,993) from the National Health Interview Survey with linked data retrieved from the National Death Index served as our study participants. Cox proportional-hazards models were used to assess associations between pre- and post-diabetes and all-cause and cause-specific mortality. Results: Over a median follow-up period of 13 years, 2,350 all-cause, 698 cancer, and 506 CVD deaths occurred. Among all cancer survivors, patients with diabetes had greater risk of: all-cause mortality [hazard ratio (HR) 1.35, 95% CI = 1.27-1.43], cancer-specific mortality (HR: 1.14, 95% CI = 1.03-1.27), CVD mortality (HR: 1.36, 95% CI = 1.18-1.55), diabetes related mortality (HR: 17.18, 95% CI = 11.51-25.64), and kidney disease mortality (HR: 2.51, 95% CI = 1.65-3.82), compared with individuals without diabetes. The risk of all-cause mortality was also higher amongst those with diabetes and specific types of cancer: breast cancer (HR: 1.28, 95% CI = 1.12-1.48), prostate cancer (HR: 1.20, 95% CI = 1.03-1.39), and colorectal cancer (HR: 1.29, 95% CI = 1.10-1.50). Diabetes increased the risk of cancer-specific mortality among colorectal cancer survivors (HR: 1.36, 95% CI = 1.04-1.78) compared to those without diabetes. Diabetes was associated with higher risk of diabetes-related mortality when compared to non-diabetic breast (HR: 9.20, 95% CI = 3.60-23.53), prostate (HR: 18.36, 95% CI = 6.01-56.11), and colorectal cancer survivors (HR: 12.18, 95% CI = 4.17-35.58). Both pre- and post-diagnosis diabetes increased the risk of all-cause mortality among all cancer survivors. Cancer survivors with diabetes had similar risk of all-cause and CVD mortality during the second 5 years of diabetes and above 10 years of diabetes as compared to non-diabetic patients. Conclusions: Diabetes increased the risk of all-cause mortality among breast, prostate, and colorectal cancer survivors, not for pre- or post-diagnosis diabetes. Greater attention on diabetes management is warranted in cancer survivors with diabetes.

Diabetes mellitus and cancer incidence: the Atherosclerosis Risk in Communities (ARIC) cohort study

PURPOSE

To assess the association between diabetes mellitus (DM) and the incidence of cancer at different sites.

METHODS

Data from the baseline and first three follow-up visits of the Atherosclerosis Risk in Communities (ARIC) study, an ongoing cohort study of adults from four American communities, were used in this study. Of 15,792 persons aged 45-64 years old who participated in the baseline visit, the data of 15,118 participants were available for this study. For each cancer site, a conditional stratified Poisson regression model was fitted to estimate the adjusted relative rate and 95% confidence interval (adj. RR, 95% CI) of its incidence in diabetics compared to non-diabetics.

RESULTS

We excluded 850 participants with a history of cancer at baseline and 149 participants who developed cancer during 2 years after enrollment, leaving a total of 14,119 participants of whom 1721 were diabetics. Independent of age, body mass index, alcohol consumption, and physical activity, DM decreased the risk of all cancers combined (adj. RR: 0.77, 95% CI: 0.60, 0.98) and the risk of prostate cancer (adj. RR: 0.51, 95% CI: 0.27, 0.97) and increased the risk of colorectal cancer in non-menopausal women (adj. RR: 12.08, 95% CI: 2.06, 70.94).

CONCLUSIONS

In conclusion, DM may be associated with an increased risk of colorectal cancer in non-menopausal women and a decreased risk of prostate cancer and all cancers combined.

Diabetes mellitus predicts inferior survival in diffuse large B-cell lymphoma: a propensity score-matched analysis

Purpose: Diabetes mellitus (DM) is associated with elevated cancer risk and poor survival. The objective of this study was to assess the prognostic value of DM in diffuse large B-cell lymphoma (DLBCL). Methods: Five hundred and fifty-three newly diagnosed DLBCL patients whose treatments included rituximab were recruited. Propensity score-matched method was performed to balance baseline characteristics and eliminate possible bias. Multivariate Cox regression analyses screened the prognostic risk factors in relation to progression-free survival (PFS) and cancer-specific survival (CSS). Receiver-operator characteristic curves and the corresponding areas under the curve (AUC) assessed the predictive accuracy of international prognostic index (IPI) together with DM. Results: One hundred and nine patients (19.71%) had pre-existing DM. In the propensity-matched cohort, DM was associated with unfavorable PFS and CSS in rituximab era, and it was an independent risk factor for both inferior PFS and CSS, especially in patients with age ≤60 years, IPI 0-2, B symptoms and lactate dehydrogenase ≤upper limit of normal. Prediabetics also demonstrated inferior prognostic outcomes compared to patients with no diabetic tendency. DM as one additional point to IPI had larger AUC compared with IPI alone in CSS prediction and could improve the prognostic capacity of IPI. Conclusion: The results indicate that preexisting DM is an important risk factor for survival. It could help predict life expectancy and build refined prognostication models for DLBCL.

Sex- and site-specific differences in colorectal cancer risk among people with type 2 diabetes

PURPOSE

The prevalence of colorectal cancer is higher among patients with type 2 diabetes mellitus (T2D) than among patients without diabetes. Furthermore, men are at higher risk for developing colorectal cancer than women in the general population and also subsite-specific risks differ per sex. The aim was to evaluate the impact of T2D on these associations.

METHODS

A population-based matched cohort study was performed using data from the PHARMO Database Network. Patients with T2D were selected and matched (1:4) to diabetes free controls. Cox proportional hazards models were used to estimate hazard ratios (HRs) for CRC and its subsites. HRs were determined per sex and adjusted for age and socioeconomic status. The ratio of distal versus proximal colon cancer was calculated for people with T2D and controls per sex and stratified by age.

RESULTS

Over 55,000 people with T2D were matched to > 215,000 diabetes free controls. Men and women with T2D were 1.3 times more likely to develop colorectal cancer compared to controls. Men with T2D were at higher risk to develop distal colon cancer (hazard ratio (95% confidence interval), 1.42 (1.08-1.88)), and women with T2D were at higher risk for developing proximal colon cancer (hazard ratio (95% confidence interval), 1.58 (1.13-2.19)). For rectal cancer, no statistically significant risk was observed for both men and women.

CONCLUSIONS

Sex-specific screening strategies and prevention protocols should be considered for people with T2D. More tailored screening strategies may optimize the effectiveness of colorectal cancer screening in terms of reducing incidence and mortality.

Type 2 diabetes and risk of colorectal cancer in two large U.S. prospective cohorts

Background

Previous studies have shown a positive association between type 2 diabetes (T2D) and colorectal cancer (CRC) risk. However, it is uncertain whether this association differs by duration of T2D or sex. We thus investigated the associations of T2D and its duration with the risk of incident CRC.

Methods

We followed 87,523 women from the Nurses’ Health Study (1980–2012) and 47,240 men from the Health Professionals Follow-up Study (1986–2012). Data on physician-diagnosed T2D was collected at baseline with a questionnaire and updated biennially. Cox regression models were used to estimate multivariable-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs).

Results

We documented 3000 CRC cases during up to 32 years of follow-up. Among men, T2D was associated with increased risk of CRC compared to those without T2D (HR: 1.42; 95% CI: 1.12–1.81). This positive association persisted in sensitivity analyses by excluding CRC identified within 1 year of diabetes diagnosis and patients with T2D who used hypoglycaemic medications. Among women, T2D was positively, but not statistically significantly, associated with CRC risk (HR: 1.17; 95% CI: 0.98–1.39).

Conclusions

Our findings support that T2D was associated with a moderately higher risk of developing CRC in men; a weaker, nonsignificant positive association was observed in women.

Risk of colon cancer recurrence in relation to diabetes

PURPOSE

To describe the association between diabetes and colon cancer recurrence.

METHODS

We conducted a cohort study at two integrated health care delivery systems in the United States. Using tumor registry data, we identified patients aged ≥ 18 years when diagnosed with stage I-IIIA adenocarcinomas of the colon during 1995-2014. Pre-existing diabetes was ascertained via diagnosis codes. Medical records were reviewed for eligibility and to abstract recurrence and covariate information. Recurrence was ascertained beginning 90 days after the end of colon cancer treatment (i.e., cohort entry). Recurrence of any cancer or a new primary cancer at any site was a secondary outcome. We used multivariable Cox proportional hazards models to estimate hazard ratios (HR) and 95% confidence intervals (CIs) for the associations between diabetes at cohort entry and study outcomes.

RESULTS

Among the 1,923 eligible patients, 393 (16.7%) had diabetes at cohort entry. Diabetes was not associated with recurrence (HR 0.87; 95% CI 0.56-1.33) or with any subsequent cancer (HR 1.09; 95% CI 0.85-1.40). When the definition of recurrence included second primary colorectal cancer, risk was non-significantly higher in patients with diabetes than without diabetes.

CONCLUSIONS

The risk of colon cancer recurrence appears to be similar in patients with and without diabetes at diagnosis.

IMPACT

Future studies should evaluate the association between diabetes and colorectal cancer outcomes, especially second primary colon cancers, in larger populations.

Metformin and blood cancers

Type 2 diabetes mellitus and cancer are correlated with changes in insulin signaling, a pathway that is frequently upregulated in neoplastic tissue but impaired in tissues that are classically targeted by insulin in type 2 diabetes mellitus. Many antidiabetes treatments, particularly metformin, enhance insulin signaling, but this pathway can be inhibited by specific cancer treatments. The modulation of cancer growth by metformin and of insulin sensitivity by anticancer drugs is so common that this phenomenon is being studied in hundreds of clinical trials on cancer. Many meta-analyses have consistently shown a moderate but direct effect of body mass index on the incidence of multiple myeloma and lymphoma and the elevated risk of leukemia in adults. Moreover, new epidemiological and preclinical studies indicate metformin as a therapeutic agent in patients with leukemia, lymphomas, and multiple myeloma. In this article, we review current findings on the anticancer activities of metformin and the underlying mechanisms from preclinical and ongoing studies in hematologic malignancies.

Rosiglitazone diminishes the high-glucose-induced modulation of 5-fluorouracil cytotoxicity in colorectal cancer cells

Colorectal cancer (CRC) is the third most leading cause of morbidity and mortality throughout the world. 5-fluorouracil (5-FU), which is often administrated to disrupt carcinogenesis, was found to elevate blood glucose level among CRC patients. Thus, this study was conducted to evaluate the influence of rosiglitazone on antiproliferative effect of 5-FU using cellular model. Two human colonic carcinoma cell lines (HCT 116 and HT 29) were cultured in the presence of 5-FU, rosiglitazone or in combination under normal and high glucose concentration. The drug cytotoxicity was evaluated using the MTT assay whereas the assessment of cell cycle was carried out using the flow cytometry technique. Combination index (CI) method was used to determine the drug interaction between rosiglitazone and 5-FU. High glucose diminished the cytotoxic effect of 5-FU but at a high drug dosage, this effect could be overcome. Cell cycle analysis demonstrated that 5-FU and rosiglitazone caused G1-phase arrest and S-phase arrest, respectively. CI values indicated that rosiglitazone exerted synergistic effect on 5-FU regardless of glucose levels. This study is the first to demonstrate the influence of rosiglitazone on cytotoxicity of 5-FU under normal or high glucose level. Rosiglitazone may be a promising drug for enhancing the efficacy of 5-FU in the treatment of CRC associated with hyperglycemia.

Effect of home-based exercise intervention on fasting insulin and Adipocytokines in colorectal cancer survivors: a randomized controlled trial

BACKGROUND AND AIMS

Elevated circulating insulin is associated with increased risk of recurrence and cancer mortality in early-stage colorectal cancer (CRC). We conducted a randomized controlled trial to determine the effect of a 12-week home-based exercise program on fasting insulin, adipocytokines, and physical function in CRC survivors.

METHODS

One hundred and twenty-three stage II-III CRC patients were randomly assigned to either a home-based exercise (n=62) or standard care control group (n=61) for 12weeks. Home-based exercise consisted of aerobic and resistance training, with a goal of obtaining ≥18 metabolic equivalent task (MET)-h/wk. Participants in the exercise group were instructed to participate in >18MET-h/wk. of aerobic and resistance exercise while the participants in the control group were asked to maintain their usual daily activity. The primary outcome was fasting insulin levels. Secondary outcomes were adiponectin, TNF-α levels and 6min walk distance from baseline to post-intervention.

RESULTS

After the 12-weeks, moderate-vigorous physical activity participation increased from 9.1±14.7MET-h/wk. to 26.6±21.7MET-h/wk. in the exercise group, with no change in the control group (p<0.01 for group and time interaction). Circulating insulin level decreased by 1μU/ml (6.0±3.9 vs. 5.0±3.5, p=0.009) in the exercise group with no change in the control group (p=0.022 for group and time interaction). A similar trend was observed in TNF-α (p=0.030 for group and time interaction). Six minute walk distance increased by 25.2m in the exercise group with no change in the control group (p=0.061 for group and time interaction).

CONCLUSIONS

The 12week home-based exercise program increased level of physical activity and decreased circulating insulin levels in CRC survivors.

The expanding role of metformin in cancer: an update on antitumor mechanisms and clinical development

Metformin has been used for nearly a century to treat type 2 diabetes mellitus. Epidemiologic studies first identified the association between metformin and reduced risk of several cancers. The anticancer mechanisms of metformin involve both indirect or insulin-dependent pathways and direct or insulin-independent pathways. Preclinical studies have demonstrated metformin's broad anticancer activity across a spectrum of malignancies. Prospective clinical trials involving metformin in the chemoprevention and treatment of cancer now number in the hundreds. We provide an update on the anticancer mechanisms of metformin and review the results thus far available from prospective clinical trials investigating metformin's efficacy in cancer.

Outcomes of preexisting diabetes mellitus in breast, colorectal, and prostate cancer

Purpose

Preexisting diabetes is associated with increased morbidity and mortality in cancer. We examined the impact of incident cancer on the long-term outcomes of diabetes.

Methods

Using the United Kingdom Clinical Practice Research Datalink, we identified three cohorts of diabetes patients subsequently diagnosed with breast, colorectal, or prostate cancer, each matched to diabetic noncancer controls. Patients were required to have survived at least 1 year after cancer diagnosis (cases) or a matched index date (controls), and were followed up to 10 years for incident microvascular and macrovascular complications and mortality. Multivariate competing risks regression analyses were used to compare outcomes between cancer patients and controls.

Results

Overall, there were 3382 cancer patients and 11,135 controls with 59,431 person-years of follow-up. In adjusted analyses, there were no statistically significant (p ≤ 0.05) differences in diabetes complication rates between cancer patients and their controls in any of the three cancer cohorts. Combined, cancer patients were less likely (adjusted hazard ratio [HR] 0.88; 95% CI = 0.79–0.98) to develop retinopathy. Cancer patients were more likely to die of any cause (including cancer), but prostate cancer patients were less likely to die of causes associated with diabetes (HR 0.61; 95% CI = 0.43–0.88).

Conclusions and implications

There is no evidence that incident cancer had an adverse impact on the long-term outcomes of preexisting diabetes.

Implications for Cancer Survivors

These findings are important for cancer survivors with preexisting diabetes because they suggest that substantial improvements in the relative survival of several of the most common types of cancer are not undermined by excess diabetes morbidity and mortality.

Enemies or weapons in hands: investigational anti-diabetic drug glibenclamide and cancer risk

Epidemiological evidence suggests that diabetes is associated with elevated cancer risk through the actions of hyperglycemia, hyperinsulinemia and chronic inflammation. Metformin, a first-line medication for type 2 diabetes mellitus, arouses growing concerns on its anti-cancer effect. However, data regarding the effect of glibenclamide on tumor growth and cancer risk are less consistent, which may be a potential anti-cancer drug. Areas covered: In this review, we clarified probable underlying mechanisms in preclinical studies and reviewed epidemiological evidence on glibenclamide's cancer risk in clinical studies. Glibenclamide inhibited carcinogenesis through ATP-binding cassette protein super-family and ATP-sensitive potassium channels, while majority of clinical researches reported an increased or non-significant elevated cancer risk of glibenclamide users compared with metformin users. Other sulfonylureas and diarylsulfonylureas were also briefly introduced. Expert opinion: The inconsistency between the results of studies was probably ascribed to undiscovered mechanisms, confounding factors, inconsistent comparators and publication bias. Existing clinical trials were prone to be afflicted by time-related bias including immortal time bias, time-window bias, and time-lag bias. Glibenclimiade could be a promising and well-tolerated anti-neoplastic drug targeting ATP-binding cassette protein super-family and KATP channels, but its efficacy still needs to be proven in well-designed long-term randomized controlled clinical trials.

Diabetes-induced mechanophysiological changes in the small intestine and colon

The disorders of gastrointestinal (GI) tract including intestine and colon are common in the patients with diabetes mellitus (DM). DM induced intestinal and colonic structural and biomechanical remodeling in animals and humans. The remodeling is closely related to motor-sensory abnormalities of the intestine and colon which are associated with the symptoms frequently encountered in patients with DM such as diarrhea and constipation. In this review, firstly we review DM-induced histomorphological and biomechanical remodeling of intestine and colon. Secondly we review motor-sensory dysfunction and how they relate to intestinal and colonic abnormalities. Finally the clinical consequences of DM-induced changes in the intestine and colon including diarrhea, constipation, gut microbiota change and colon cancer are discussed. The final goal is to increase the understanding of DM-induced changes in the gut and the subsequent clinical consequences in order to provide the clinicians with a better understanding of the GI disorders in diabetic patients and facilitates treatments tailored to these patients.

Diabetes mellitus type 2 and subsite-specific colorectal cancer risk in men and women: results from the Netherlands Cohort Study on diet and cancer

BACKGROUND

Type 2 diabetes mellitus (T2DM) is associated with an increased risk of colorectal cancer (CRC); however, studies differentiating between subsites of CRC are limited. We investigated how diabetes mellitus (DM) was associated with subsite-specific CRC risk in men and women.

METHODS

The Netherlands Cohort Study on diet and cancer is a prospective study among 120 852 men and women aged 55-69 years old at baseline in 1986. Information on DM, anthropometric, dietary and lifestyle factors was self-reported at baseline. T2DM was defined as the diagnosis of DM after 30 years of age. Incident CRC cases were identified by record linkage with the Netherlands cancer registry and the Dutch pathology registry. After 17.3 years of follow-up, 1735 incident male CRC cases and 1321 female CRC cases were available for analyses. Subsite-specific hazard ratios (HRs) for CRC were estimated in case-cohort analyses using Cox regression.

RESULTS

At baseline, 3.1% of subcohort members reported T2DM, of whom 80% were diagnosed after 50 years of age. Multivariable-adjusted models showed that the risk of proximal colon cancer was significantly increased in women with T2DM versus women without T2DM (HR=1.80, 95% confidence interval: 1.10-2.94). There was no association between T2DM and the risk of overall CRC, distal colon cancer and rectal cancer in women. In men, T2DM was not associated with overall CRC (HR=0.98, 95% confidence interval: 0.64-1.50), or with risk at any subsite.

CONCLUSIONS

This prospective study showed an increased risk of proximal colon cancer in women with T2DM compared with non-T2DM women.

Association between Metformin Use and Survival in Nonmetastatic Rectal Cancer Treated with a Curative Resection: A Nationwide Population Study

Purpose

Metformin is associated with an anticancer effect. However, the effects of metformin in rectal cancer are controversial. This study investigated the impact of metformin on the survival of patients with diabetes mellitus and nonmetastatic rectal cancer who underwent curative surgery.

Materials and Methods

The database was provided by the Korea Center Cancer Registry and National Health Insurance Service of the Republic of Korea. A cohort of patients with newly diagnosed rectal cancer between 2005 and 2011 was identified. Drug exposure was defined as receiving the oral hypoglycemic agent for at least 90 days over the period from 6 months before the initial diagnosis of rectal cancer to the last follow-up.

Results

A total of 4,503 patients were prescribed oral hypoglycemic agents and classified as the diabetic group, of which 3,694 patients received metformin for at least 90 days. Unadjusted analyses showed a significantly higher overall survival (hazard ratio, 0.596; 95% confidence interval, 0.506 to 0.702) and rectal cancer-specific survival (hazard ratio, 0.621; 95% confidence interval, 0.507 to 0.760) in the metformin group than in the nonmetformin group. The adjusted overall survival (hazard ratio, 0.631; 95% confidence interval, 0.527 to 0.755) and cancer-specific survival (hazard ratio, 0.598; 95% confidence interval, 0.479 to 0.746) in the group with a medication possession ratio of 80% or greater was significantly higher than in the group with a medication possession ratio of less than 80%.

Conclusion

Metformin use is associated with overall and cancer-specific survival in diabetic patients with a nonmetastatic rectal cancer treated with a curative resection.

A retrospective study on the role of diabetes and metformin in colorectal cancer disease survival

BACKGROUND

Recent studies have suggested an effect of metformin on mortality for patients with both diabetes and colorectal cancer (crc). However, the literature is contradictory, with both positive and negative effects being identified. We set out to determine the effect of metformin with respect to prognosis in crc patients.

METHODS

After a retrospective chart review of crc patients treated at the Cancer Centre of Southeastern Ontario, Kaplan-Meier analyses and Cox proportional hazards regression models were used to compare overall survival (os) in patients with and without diabetes.

RESULTS

We identified 1304 crc patients treated at the centre. No significant differences between the diabetic and nondiabetic groups were observed with respect to tumour pathology, extent of metastatic disease, time or toxicity of chemotherapy, and the os rate (1-year os: 85.6% vs. 86.4%, p = 0.695; 2-year os: 73.6% vs. 77.0%, p = 0.265). In subgroup analysis, diabetic patients taking metformin survived significantly longer than their counterparts taking other diabetes treatments (os for the metformin group: 91% at 1 year; 80.5% at 2 years; os for the group taking other treatments, including diet control: 80.6% at 1 year, 67.4% at 2 years). Multivariate analysis suggests that patients with diabetes taking treatments other than metformin experience worse survival (p = 0.025).

CONCLUSIONS

Our results suggest that crc patients with diabetes, excluding those taking metformin, might have a worse crc prognosis. Taking metformin appears to have a positive association with prognosis. The protective nature of metformin needs further evaluation in prospective analyses.

Associations Between Parameters of Glucose and Lipid Metabolism and Risk of Colorectal Neoplasm

BACKGROUND

Diabetes and dyslipidemia have been linked to an increased risk of colorectal neoplasm (CRN). However, previous studies evaluating these associations have shown inconsistent results, and large-scale studies are few in number.

AIM

To investigate the associations between the parameters of glucose and lipid metabolism and the presence of CRN.

METHODS

A cross-sectional study was performed on 38,490 Korean adults aged ≥30 years undergoing their first colonoscopy as part of routine preventive health care between 2010 and 2011.

RESULTS

The prevalence of overall CRN increased with increasing levels of glucose, hemoglobin A1c (HbA1c), insulin, homeostasis model assessment of insulin resistance (HOMA-IR), triglycerides, total cholesterol, low-density lipoprotein cholesterol (LDL-C), and apolipoprotein B (ApoB) and with decreasing level of apolipoprotein A1 (ApoA1). The adjusted prevalence ratios for overall CRN comparing the fourth with the first quartiles of fasting glucose, HbA1c, insulin, HOMA-IR, triglycerides, total cholesterol, LDL-C, ApoB, and ApoA-1 were 1.83 (95% CI 1.62-2.06), 1.17 (95% CI 1.03-1.33), 1.09 (95% CI 0.97-1.23), 1.22 (95% CI 1.08-1.37), 1.31 (95% CI 1.16-1.48), 1.19 (95 % CI 1.07-1.33), 1.38 (95% CI 1.23-1.54), 1.30 (95% CI 1.14-1.47), and 0.85 (95% CI 0.76-0.95), respectively. There was also a significant association between higher levels of glucose, LDL-C, and ApoB with a higher prevalence of advanced CRN. Moreover, the risk of CRN increased further in cases in which the parameters of glucose metabolism and lipid metabolism worsened simultaneously.

CONCLUSIONS

The levels of parameters of glucose and lipid metabolism are significantly associated with the prevalence of CRN. Altered glucose and lipid metabolism may contribute to the development of CRN.

Insulin therapy and the risk of colorectal cancer in patients with type 2 diabetes: a meta-analysis of observational studies

AIMS

Several epidemiological studies have reported inconsistent associations between insulin therapy and the risk of colorectal cancer (CRC) in patients with type 2 diabetes mellitus. We performed this meta-analysis of observational studies to evaluate the effect of insulin therapy on the risk of CRC.

METHODS

We carried out a systematic search of PubMed, Embase and the Cochrane Library Central database between January 1966 and August 2013. Fixed-effects and random-effects models were used to estimate the pooled relative risk (RR) and corresponding 95% confidence interval (CI).

RESULTS

A total of 12 epidemiological studies were included in the present meta-analysis, involving a total of 7947 CRC cases and 491 384 participants. There was significant heterogeneity among the studies, but no publication bias. Insulin therapy significantly increased the risk of CRC [RR = 1.69, 95% CI (1.25, 2.27)]. When the various studies were stratified by study design, we found that insulin use was associated with a statistically significant 115% higher risk of CRC among case-control studies [RR = 2.15, 95% CI (1.41, 3.26)], but not among cohort studies [RR = 1.25, 95% CI (0.95, 1.65)]. Furthermore, a significant association was noted among studies conducted in USA [RR = 1.73, 95% CI (1.15, 2.60)] and Asia [RR = 2.55, 95% CI (2.14, 3.04)], but not in Europe [RR = 1.20, 95% CI (0.92, 1.57)].

CONCLUSIONS

The present meta-analysis suggests that insulin therapy may increase the risk of CRC. More prospective cohort studies with longer follow-up durations are warranted to confirm this association. Furthermore, future studies should report results stratified by gender and race and should adjust the results by more confounders.

Development and validation of risk prediction algorithms to estimate future risk of common cancers in men and women: prospective cohort study

OBJECTIVE

To derive and validate a set of clinical risk prediction algorithm to estimate the 10-year risk of 11 common cancers.

DESIGN

Prospective open cohort study using routinely collected data from 753 QResearch general practices in England. We used 565 practices to develop the scores and 188 for validation.

SUBJECTS

4.96 million patients aged 25-84 years in the derivation cohort; 1.64 million in the validation cohort. Patients were free of the relevant cancer at baseline.

METHODS

Cox proportional hazards models in the derivation cohort to derive 10-year risk algorithms. Risk factors considered included age, ethnicity, deprivation, body mass index, smoking, alcohol, previous cancer diagnoses, family history of cancer, relevant comorbidities and medication. Measures of calibration and discrimination in the validation cohort.

OUTCOMES

Incident cases of blood, breast, bowel, gastro-oesophageal, lung, oral, ovarian, pancreas, prostate, renal tract and uterine cancers. Cancers were recorded on any one of four linked data sources (general practitioner (GP), mortality, hospital or cancer records).

RESULTS

We identified 228,241 incident cases during follow-up of the 11 types of cancer. Of these 25,444 were blood; 41,315 breast; 32,626 bowel, 12,808 gastro-oesophageal; 32,187 lung; 4811 oral; 6635 ovarian; 7119 pancreatic; 35,256 prostate; 23,091 renal tract; 6949 uterine cancers. The lung cancer algorithm had the best performance with an R(2) of 64.2%; D statistic of 2.74; receiver operating characteristic curve statistic of 0.91 in women. The sensitivity for the top 10% of women at highest risk of lung cancer was 67%. Performance of the algorithms in men was very similar to that for women.

CONCLUSIONS

We have developed and validated a prediction models to quantify absolute risk of 11 common cancers. They can be used to identify patients at high risk of cancers for prevention or further assessment. The algorithms could be integrated into clinical computer systems and used to identify high-risk patients.

WEB CALCULATOR

There is a simple web calculator to implement the Qcancer 10 year risk algorithm together with the open source software for download (available at http://qcancer.org/10yr/).

Racial disparities and colorectal cancer survival in older adults with and without diabetes mellitus

BACKGROUND AND AIM

To investigate whether pre-existing diabetes modifies racial disparities in colorectal cancer (CRC) survival.

METHODS

We analyzed prospective data from 16 977 patients (age ≥ 67 years) with CRC from the Surveillance Epidemiology and End Results (SEER)-Medicare database. SEER registries included data on demographics, tumor characteristics, and treatment. Medicare claims were used to define pre-existing diabetes and comorbid conditions. Mortality was confirmed in both sources.

RESULTS

At baseline, 1332 (8%) were African Americans and 26% had diabetes (39% in blacks; 25% in whites). From 2000 to 2005, more than half of the participants died (n = 8782, 52%). This included 820 (62%) deaths (23.8 per 100 person-years) among blacks, and 7962 (51%) deaths (16.6 per 100 person-years) among whites. Among older adults with diabetes, blacks had significantly higher risk of all-cause and CRC mortality after adjustments for demographic characteristics (hazard ratio [HR], 95% confidence interval [CI]: 1.21 [1.08-1.37] and 1.21 [1.03-1.42]), respectively, but these associations attenuated to null after additional adjustments for cancer stage and grade. Among adults without diabetes, the risk of all-cause mortality (HR [95% CI]: 1.14 [1.04-1.25]) and CRC mortality (HR [95% CI]: 1.21 [1.08-1.36]) remained higher in blacks than whites in fully adjusted models that included demographic variables, cancer stage, grade, treatments, and comorbidities.

CONCLUSIONS

Among older adults with CRC, diabetes is an effect modifier on the relationship between race and mortality. Racial disparities in survival were explained by demographics, cancer stage, and grade in patients with diabetes.

Antihyperglycaemic therapies and cancer risk

AIMS

This review is aimed at highlighting the potential mitogenic/tumour growth-promoting or antimitogenic/tumour growth-inhibiting effects of the main antihyperglycaemic drug classes.

METHODS

We review and discuss the most current studies evaluating the association between antidiabetic medications used in clinical practice and malignancies as described so far.

RESULTS

Metformin seems to be the only antidiabetic drug to exert protective effects both on monotherapy and also when combined with other oral antidiabetic drugs or insulins in several site-specific cancers. In contrast, several other drug classes may increase cancer risk. Some reason for concern remains regarding sulphonylureas and also the incretin-based therapies regarding pancreas and thyroid cancers and the sodium glucose cotransporter-2 inhibitors as well as pioglitazone regarding bladder cancer. The majority of meta-analyses suggest that there is no evidence for a causal relationship between insulin glargine and elevated cancer risk, although the studies have been controversially discussed. For α-glucosidase inhibitors and glinides, neutral or only few data upon cancer risk exist.

CONCLUSION

Although the molecular mechanisms are not fully understood, a potential risk of mitogenicity and tumour growth promotion cannot be excluded in case of several antidiabetic drug classes. However, more large-scale, randomized, well-designed clinical studies with especially long follow-up time periods are needed to get reliable answers to these safety issues.

CARING (CAncer Risk and INsulin analoGues): the association of diabetes mellitus and cancer risk with focus on possible determinants - a systematic review and a meta-analysis

Background:

Patients suffering from diabetes mellitus (DM) may experience an increased risk of cancer; however, it is not certain whether this effect is due to diabetes per se.

Objective:

To examine the association between DM and cancers by a systematic review and meta-analysis according to the PRISMA guidelines.

Data Sources:

The systematic literature search includes Medline at PubMed, Embase, Cinahl, Bibliotek.dk, Cochrane library, Web of Science and SveMed+ with the search terms: “Diabetes mellitus”, “Neoplasms”, and “Risk of cancer”.

Study Eligibility Criteria:

The included studies compared the risk of cancer in diabetic patients versus non-diabetic patients. All types of observational study designs were included.

Results:

Diabetes patients were at a substantially increased risk of liver (RR=2.1), and pancreas (RR=2.2) cancer. Modestly elevated significant risks were also found for ovary (RR=1.2), breast (RR=1.1), cervix (RR=1.3), endometrial (RR=1.4), several digestive tract (RR=1.1-1.5), kidney (RR=1.4), and bladder cancer (RR=1.1). The findings were similar for men and women, and unrelated to study design. Meta-regression analyses showed limited effect modification of body mass index, and possible effect modification of age, gender, with some influence of study characteristics (population source, cancer- and diabetes ascertainment).

Limitations:

Publication bias seemed to be present. Only published data were used in the analyses.

Conclusions:

The systematic review and meta-analysis confirm the previous results of increased cancer risk in diabetes and extend this to additional cancer sites. Physicians in contact with patients with diabetes should be aware that diabetes patients are at an increased risk of cancer.

Association between markers of glucose metabolism and risk of colorectal adenoma

BACKGROUND & AIMS

Diabetes is a risk factor for colorectal cancer. We studied the association between markers of glucose metabolism and metabolic syndrome and the presence of colorectal adenomas in a large number of asymptomatic men and women attending a health screening program in South Korea. We also investigated whether these associations depend on adenoma location.

METHODS

In a cross-sectional study, we measured fasting levels of glucose, insulin, hemoglobin A1c, and C-peptide and calculated homeostatic model assessment (HOMA) values (used to quantify insulin resistance) for 19,361 asymptomatic South Korean subjects who underwent colonoscopy examinations from January 2006 to June 2009. Participants completed a standardized self-administered health questionnaire and a validated semiquantitative food frequency questionnaire. Blood samples were collected on the day of the colonoscopy; fasting blood samples were also collected. Robust Poisson regression was used to model the associations of glucose markers with the prevalence of any adenoma.

RESULTS

Using detailed multivariable-adjusted dose-response models, the prevalence ratios (aPR, 95% confidence interval [CI]) for any adenoma, comparing the 90th with the 10th percentile, were 1.08 (1.00-1.16; P = .04) for fasting glucose, 1.07 (0.99-1.15; P = .10) for insulin, 1.09 (1.02-1.18, P = .02) for HOMA, 1.09 (1.01-1.17; P = .02) for hemoglobin A1c, and 1.14 (1.05-1.24; P = .002) for C-peptide. The corresponding ratios for nonadvanced adenomas were 1.11 (0.99-1.25; P = .08), 1.10 (0.98-1.24; P = .12), 1.15 (1.02-1.29; P = .02), 1.14 (1.01-1.28; P = .03), and 1.20 (1.05-1.37; P = .007), respectively. The corresponding ratios for advanced adenomas were 1.32 (0.94-1.84; P = .11), 1.23 (0.87-1.75; P = .24), 1.30 (0.92-1.85; P = .14), 1.13 (0.79-1.61; P = .50), and 1.67 (1.15-2.42; P = .007), respectively. Metabolic syndrome was associated with the prevalence of any adenoma (aPR, 1.18; 95% CI, 1.13-1.24; P < .001), nonadvanced adenoma (aPR, 1.30; 95% CI, 1.20-1.40; P < .001), and advanced adenoma (aPR, 1.42; 95% CI, 1.14-1.78; P = .002). Associations were similar for adenomas located in the distal versus proximal colon.

CONCLUSIONS

Increasing levels of glucose, HOMA values, levels of hemoglobin A1c and C-peptide, and metabolic syndrome are significantly associated with the prevalence of adenomas. Adenomas should be added to the list of consequences of altered glucose metabolism.

Insulin therapy and risk of colorectal cancer: an updated meta-analysis of epidemiological studies

OBJECTIVE

An increasing number of studies show that exogenous insulin therapy may promote colorectal carcinogenesis. However, the results of the association between insulin therapy and risk of colorectal cancer (CRC) among type 2 diabetes patients are inconsistent. The purpose of our study is to examine the effect of insulin therapy on CRC risk among patients with type 2 diabetes in an updated meta-analysis.

RESEARCH DESIGN AND METHODS

Medline and Embase were searched for the reference lists of pertinent articles published from January 1970 to April 2013. Two investigators independently extracted the data and reached consensus on the inclusion and exclusion criteria. Pooled relative risks and 95% confidence intervals were calculated with a random-effects model.

RESULTS

Analysis of six studies, including 374,950 participants, showed that compared with non-insulin or metformin treatment, insulin treatment was associated with an increase of 37% in the risk of colorectal neoplasm among patients with type 2 diabetes, with moderate heterogeneity (I2=40%). The sensitivity analysis showed that exclusion of one small case-control study had no appreciable changes on the pooled results. Subgroup analyses suggested that there were significant positive associations between insulin therapy and risk of CRC in some subgroups, rather than all subgroups.

CONCLUSIONS

Our meta-analysis supports a relationship between insulin therapy and increased risk of CRC in patients with type 2 diabetes. Because of bias and confounding of included studies, caution is needed when interpreting our results. Further investigations are needed.

Glucocorticoid-induced hyperglycemia is prevalent and unpredictable for patients undergoing cancer therapy: an observational cohort study

BACKGROUND

Patients with cancer are often treated with glucocorticoids (gcs) as part of therapy, which may cause hyperglycemia. We sought to define the prevalence of, and risk factors for, hyperglycemia in this setting.

METHODS

Adult patients taking gc as part of therapy protocols for primary brain tumour or metastasis, for lymphoma, or for bone marrow transplant (bmt) were screened with random glucometer measurements taken at least 3 hours after the last dose gcs.

RESULTS

We screened 90 patients [44.4% women, 55.6% men; mean age: 59.6 years (range: 25-82 years); mean body mass index (bmi): 26.4 kg/m(2) (range: 15.8-45.3 kg/m(2))] receiving gc as part of cancer treatment. Mean total daily gc dose in the group was 238.5 mg (range: 30-1067 mg) hydrocortisone equivalents. Hyperglycemia (glucose ≥ 8.0 mmol/L) was found in 58.9% (53 of 90), and diabetes mellitus (dm)-range hyperglycemia (glucose ≥ 11.1 mmol/L) in 18.9% (17 of 90). The mean time from gc ingestion to glucometer testing was 5.5 hours (range: 3-20 hours). Presence of hyperglycemia did not correlate with traditional dm risk factors such as age, sex, bmi, and personal or family history of dm. A longer interval from gc dose to testing (p < 0.05), a higher gc dose (p = 0.04), and a shorter interval between the preceding meal and testing (p = 0.02) were risk factors for hyperglycemia in some patient groups.

CONCLUSIONS

Glucocorticoid-induced hyperglycemia is common in patients undergoing cancer treatment and cannot be predicted by traditional risk factors for dm. We recommend that all cancer patients receiving gc be screened for hyperglycemia at least 4-6 hours after gc administration.

Diabetes, antihyperglycemic medications and cancer risk: smoke or fire?

OBJECTIVE

The aim of this review article is to discuss the epidemiological links between diabetes and cancer; the potential biological mechanisms linking diabetes, obesity and cancer; the risk of cancer associated with antidiabetic medications.

METHODS

The data discussed in this review were obtained from the American Association of Clinical Endocrinologists Consensus Conference on Diabetes and Cancer, held in New York, NY, USA, September 2012.

RESULTS

The results of these studies demonstrate a significant association between diabetes and the risk of multiple cancers, including hepatocellular, pancreatic, endometrial, colorectal, breast, kidney, bladder, gastric, and ovarian cancer, non-Hodgkin lymphoma, T cell lymphoma and leukemia. There are multiple potential biological mechanisms that may link type 2 diabetes, obesity and cancer. Insulin resistance and hyperinsulinemia may lead to direct activation of the insulin receptors on tumor cells and promote tumor growth. Other potential mechanisms include increased circulating, local or bioavailable insulin-like growth factor 1, hyperglycemia, dyslipidemia, increased circulating or local estrogen, adipokines and direct and indirect effects of inflammatory cytokines. Epidemiological studies have had conflicting results regarding the associations between various classes of antidiabetic medication and cancer development. Animal studies have demonstrated increased tumor growth with certain medications, but their relevance to humans is uncertain. Metformin may, however, have protective effects on cancer development and may improve survival in patients with cancer.

CONCLUSION

We describe the current understanding of the links among diabetes, antidiabetic medication and cancer risk. We highlight some of the issues that should be addressed in the future to prevent cancer development and death in those with diabetes.

Eating frequency and risk of colorectal cancer

PURPOSE

Eating frequency is a modifiable aspect of dietary behavior that may affect risk of colorectal cancer (CRC). Although most previous case-control studies indicate a positive association, two prospective studies suggest an inverse association between eating frequency and CRC risk, with evidence of effect modification by diet composition. We examined the association between eating frequency and CRC in a large, prospective cohort study, and explored whether this relationship was modified by sex, coffee consumption, or dietary glycemic load.

METHODS

Between 2000 and 2002, 67,912 western Washington residents aged 50-76 reported average daily meal and snack frequency using a mailed questionnaire as part of the vitamins and lifestyle study. Participants were followed for CRC through linkage with SEER through 2008, over which time 409 CRC cases developed. Hazard Ratios and 95 % Confidence Intervals were obtained using Cox regression.

RESULTS

In age- and sex-adjusted models higher (5+ times/d) vs. lower (1-2 times/d) eating frequency was associated with a HR of 0.62 (95 % CI 0.43-0.88, Ptrend = 0.001). However, following further adjustment for BMI, race/ethnicity, alcohol, and other known CRC risk factors, the relationship was no longer statistically significant (HR: 0.76; 95 % CI 0.51, 1.14). No effect modification was observed by sex (Pinteraction = 0.45), coffee consumption (Pinteraction = 0.44), or dietary glycemic load (Pinteraction = 0.90). In subgroup analyses by tumor site, higher vs. lower eating frequency was associated with lower risk for colon (HR 0.65 95 % CI 0.39-1.07, Ptrend = 0.04), but not rectal cancers (HR = 1.08 95 % CI 0.54-2.18, Ptrend = 0.94).

CONCLUSION

The weak inverse association observed between eating frequency and CRC is consistent with findings from other prospective studies. Modification of this relationship by diet quality and participant characteristics should be considered in the future studies.

Increased risk of colon cancer in men in the pre-diabetes phase

BACKGROUND

Historically, studies exploring the association between type 2 diabetes mellitus (DM) and cancer lack accurate definition of date of DM onset, limiting temporal analyses. We examined the temporal relationship between colon cancer risk and DM using an electronic algorithm and clinical, administrative, and laboratory data to pinpoint date of DM onset.

METHODS

Subjects diagnosed with DM (N = 11,236) between January 1, 1995 and December 31, 2009 were identified and matched at a 5∶1 ratio with 54 365 non-diabetic subjects by age, gender, smoking history, residence, and diagnosis reference date. Colon cancer incidence relative to the reference date was used to develop Cox regression models adjusted for matching variables, body mass index, insurance status, and comorbidities. Primary outcomes measures included hazard ratio (HR) and number needed to be exposed for one additional person to be harmed (NNEH).

RESULTS

The adjusted HR for colon cancer in men before DM onset was 1.28 (95% CI 1.04-1.58, P = 0.0223) and the NNEH decreased with time, reaching 263 at DM onset. No such difference was observed in women. After DM onset, DM did not appear to alter colon cancer risk in either gender.

CONCLUSIONS

Colon cancer risk is increased in diabetic men, but not women, before DM onset. DM did not alter colon cancer risk in men or women after clinical onset. In pre-diabetic men, colon cancer risk increased as time to DM onset decreased, suggesting that the effects of the pre-diabetes phase on colon cancer risk in men are cumulative.

Intakes of heme iron and zinc and colorectal cancer incidence: a meta-analysis of prospective studies

BACKGROUND

Epidemiologic findings concerning the associations between intakes of heme iron and zinc and colorectal cancer (CRC) incidence yielded conflicting results. We aimed to investigate the associations by performing a meta-analysis of prospective studies.

METHODS

We conducted a literature search on PubMed and EMBASE databases up to December 2012 to identify the prospective studies that investigated the relationships between heme iron or zinc intake and risk of CRC. We also reviewed the bibliographies of the retrieved articles to identify additional studies. We used a random-effects model to calculate the summary relative risks (RRs) with 95 % confidence intervals (CIs).

RESULTS

Eight studies on heme iron intake and six studies on zinc intake met the inclusion criteria. The summary RR of CRC for the highest versus the lowest intake was 1.14 (95 % CI = 1.04-1.24) for heme iron and 0.83 (95 % CI = 0.72-0.94) for zinc, respectively. The observed associations were not significantly modified by subsites within the colorectum, sex, geographic area, study duration, the number of cases, or the range of intakes. In the dose-response analyses, the summary RR of CRC was 1.11 (95 % CI = 1.03-1.18) for heme iron intake of 1 mg/day, and 0.86 (95 % CI = 0.78-0.96) for zinc intake of 5 mg/day, respectively. There was little evidence of publication bias.

CONCLUSION

This meta-analysis suggests a significant positive dose-response association of heme iron intake and a significant inverse dose-response association of zinc intake with risk of CRC.