Metabolic dysregulation of the insulin-glucose axis and risk of obesity-related cancers in the Framingham heart study-offspring cohort (1971-2008)

Prediabetes and the risk of breast cancer: a meta-analysis

Background

Diabetes has been related to a higher risk of breast cancer (BC) in women. However, it remains unknown whether the incidence of BC is increased in women with prediabetes. A systematic review and meta-analysis was therefore performed to evaluate the relationship between prediabetes and risk of BC.

Methods

Observational studies with longitudinal follow-up relevant to the objective were found via searching Medline, Embase, Cochrane Library, and Web of Science. A fixed- or random-effects model was used to pool the results depending on heterogeneity.

Results

Eight prospective cohort studies and two nest case-control studies were included. A total of 1069079 community women were involved, and 72136 (6.7%) of them had prediabetes at baseline. During a mean duration follow-up of 9.6 years, 9960 (0.93%) patients were diagnosed as BC. Pooled results with a fixed-effects model showed that women with prediabetes were not associated with a higher incidence of BC as compared to those with normoglycemia (risk ratio: 0.99, 95% confidence interval: 0.93 to 1.05, p = 0.72) with mild heterogeneity (p for Cochrane Q test = 0.42, I2 = 3%). Subgroup analyses showed that study characteristics such as study design, menopausal status of the women, follow-up duration, diagnostic criteria for prediabetes, methods for validation of BC cases, and study quality scores did not significantly affect the results (p for subgroup analyses all > 0.05).

Conclusion

Women with prediabetes may not be associated with an increased risk of BC as compared to women with normoglycemia.

Association between the TyG index and TG/HDL-C ratio as insulin resistance markers and the risk of colorectal cancer

Background

No previous prospective research has explored the association of the TyG (fasting triglyceride-glucose) index and TG/HDL-C ratio as insulin resistance markers with the risk of colorectal cancer (CRC) incidence in the Northern Chinese population.

Methods

In this prospective cohort study, we included 93,659 cancer-free participants with the measurements of TyG index and TG/HDL-C ratio. Participants were divided by the quartiles of the TyG index or TG/HDL-C ratio. The associations of TyG index, TG/HDL-C ratio, and their components with CRC risk were assessed using Cox proportional hazards regression models.

Results

During a median follow-up of 13.02 years, 593 incident CRC cases were identified. Compared with the lowest quartile of the TyG index (Q1), the risk of CRC was higher in persons in the third (Q3) and highest quartiles (Q4) of the TyG index, with corresponding multivariable-adjusted HRs (95% CI) of 1.36 (1.06, 1.76) and 1.50 (1.19, 1.91), respectively. The elevated risks of CRC incidence were observed in people in the second, third, and highest quartiles of the TG/HDL-C ratio groups, with corresponding multivariable-adjusted HRs (95% CI) of 1.33 (1.05, 1.70), 1.36 (1.07, 1.73) and 1.37 (1.07, 1.75), respectively.

Conclusions

Elevated TyG index and TG/HDL-C ratio were associated with a higher risk of developing CRC among adults in Northern China.

Prospective associations of hemoglobin A1c and c-peptide with risk of diabetes-related cancers in the Cancer Prevention Study-II Nutrition Cohort

Self-reported type 2 diabetes mellitus (T2DM) is a risk factor for many cancers, suggesting its pathology relates to carcinogenesis. We conducted a case-cohort study to examine associations of hemoglobin A1c (HbA1c) and c-peptide with cancers associated with self-reported T2DM. This study was drawn from a prospective cohort of 32,383 women and men who provided blood specimens at baseline: c-peptide and HbA1c were assessed in 3,000 randomly selected participants who were cancer-free-at-baseline and an additional 2,281 participants who were cancer-free-at-baseline and subsequently diagnosed with incident colorectal, liver, pancreatic, female breast, endometrial, ovarian, bladder, or kidney cancers. Weighted-Cox regression models estimated hazards ratios (HRs) and 95% confidence intervals (CI), adjusted for covariates. C-peptide was associated with higher risk of liver cancer (per standard deviation (SD) HR: 1.80; 95%CI: 1.32-2.46). HbA1c was associated with higher risk of pancreatic cancer (per SD HR: 1.21 95%CI 1.05-1.40) and with some suggestion of higher risks for all-cancers-of-interest (per SD HR: 1.05; 95%CI: 0.99-1.11) and colorectal (per SD HR: 1.09; 95%CI: 0.98-1.20), ovarian (per SD HR: 1.18; 95%CI 0.96-1.45) and bladder (per SD HR: 1.08; 95%CI 0.96-1.21) cancers. Compared to no self-reported T2DM and HbA1c <6.5% (reference group), self-reported T2DM and HbA1c <6.5% (i.e., T2DM in good glycemic control) was not associated with risk of colorectal cancer, whereas it was associated with higher risks of all-cancers-of-interest combined (HR: 1.28; 95%CI: 1.01-1.62), especially for breast and endometrial cancers. Additional large, prospective studies are needed to further explore the roles of hyperglycemia, hyperinsulinemia, and related metabolic traits with T2DM-associated cancers to better understand the mechanisms underlying the self-reported T2DM-cancer association and to identify persons at higher cancer risk.

Biomarkers of glucose homeostasis and inflammation with risk of prostate cancer: A case-cohort study

BACKGROUND

Few prospective studies have examined biomarkers of glucose homeostasis or inflammation with prostate cancer risk by tumor stage or grade.

METHODS

We conducted a case-cohort study to examine associations of pre-diagnosis hemoglobin A1c (HbA1c), c-peptide, and c-reactive protein (CRP) with prostate cancer risk overall and stratified by tumor stage and grade. The study included 390 non-aggressive (T1-2, N0, M0 and Gleason score <8) and 313 aggressive cases (T3-4, or N1, or M1, or Gleason score 8-10) diagnosed after blood draw (1998-2001) and up to 2013, and a random sub-cohort of 1,303 cancer-free men at blood draw in the Cancer Prevention Study-II Nutrition Cohort. Prentice-weighted Cox proportional hazards regression models were used to estimate hazards ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

In the multivariable-adjusted model without body mass index (BMI), HbA1c was inversely associated with non-aggressive prostate cancer (HR per unit increase: 0.89, 95% CI: 0.80-1.00, P=0.04). Analyses stratified by tumor stage and grade separately showed that HbA1c was inversely associated with low-grade prostate cancer (HR per unit increase: 0.89, 95% CI: 0.80-1.00) and positively associated with high-grade prostate cancer (HR per unit increase: 1.15, 95% CI: 1.01-1.30). C-peptide and CRP were not associated with prostate cancer overall or by stage or grade.

CONCLUSIONS

The present study suggests that associations of hyperglycemia with prostate cancer may differ by tumor grade and stage.

IMPACT

Future studies need to examine prostate cancer by tumor stage and grade, and to better understand the role of hyperglycemia in prostate cancer progression.

Fasting Blood Glucose Variability and Unfavorable Trajectory Patterns Are Associated with the Risk of Colorectal Cancer

Background/Aims

The relationship between fasting blood glucose (FBG) variability and colorectal cancer (CRC) remains ill-defined. This study aimed to evaluate the association of FBG variability with CRC risk in the healthy population without overt diabetes.

Methods

In the data from the Korean National Health Insurance Service-Health Screening Cohort, we included individuals examined by FBG testing at least 3 times between 2002 and 2007. FBG variability was calculated using standard deviation (SD) and coefficient of variation (CV).

Results

Regarding FBG variability, an increase in the quintile of SD or CV was independently associated with CRC risk (all p for trend <0.01). When the change in FBG was classified into six trajectory patterns, unfavorable trajectory patterns (high stable and upward) were significantly associated with increased CRC risk (hazard ratio [HR] 2.30, p=0.003; HR 1.19, p=0.007, respectively). In subgroup analyses according to the sex, a significant association between FBG variability (SD or CV) and CRC risk was observed in men but not in women. The high stable and upward pattern were also associated with CRC risk in men (HR 2.47, p=0.002; HR 1.21, p=0.012) but not in women.

Conclusions

This study identified that FBG variability and unfavorable trajectory patterns were significantly associated with increased CRC risk in the healthy population without overt diabetes. Our findings suggest that FBG variability as well as FBG itself may be a predictive factor for the development of CRC.

High-sensitivity C-reactive protein, hemoglobin A1c and breast cancer risk: a nested case-control study from Alberta's Tomorrow Project cohort

PURPOSE

Our aim is to examine the associations between high-sensitivity C-reactive protein (hsCRP) and hemoglobin A1c (HbA1c), common biomarkers of inflammation and insulin resistance, respectively, with breast cancer risk, while adjusting for measures of excess body size.

METHODS

We conducted a nested case-control study within the Alberta's Tomorrow Project cohort (Alberta, Canada) including 197 incident breast cancer cases and 394 matched controls. The sample population included both pre- and postmenopausal women. Serum concentrations of hsCRP and HbA1c were measured from blood samples collected at baseline, along with anthropometric measurements, general health and lifestyle data. Conditional logistic regression was used to evaluate associations between hsCRP, HbA1c, and breast cancer risk adjusted for excess body size (body fat percentage) and other risk factors for breast cancer.

RESULTS

Higher concentrations of hsCRP were associated with elevated breast cancer risk (odds ratio [OR] 1.27; 95% confidence interval [95% CI] 1.03-1.55). The observed associations were unchanged with adjustment for body fat percentage. Higher HbA1c concentrations were not significantly associated with an increased breast cancer risk (OR 1.22; 95% CI 0.17-8.75).

CONCLUSION

These data suggest that hsCRP may be associated with elevated breast cancer risk, independent of excess body size. However, elevated concentrations of HbA1c did not appear to increase breast cancer risk in apparently healthy women.

Body mass index and risk of upper gastrointestinal cancer: A 30-year follow-up of the Linxian dysplasia nutrition intervention trial cohort

BACKGROUND

Although a number of previous studies have noted the association between body mass index (BMI) and upper gastrointestinal (UGI) cancer risk, little evidence exists in the Chinese esophageal squamous dysplasia population. This prospective study investigated the association between BMI and UGI cancer risk in the Linxian Dysplasia Nutrition Intervention Trial (NIT) cohort.

METHODS

A total of 3298 participants were included in the final analysis. Asian-specific BMI cut-offs were used to define BMI subgroups: underweight <18.5 kg/m², normal ≥18.5 to <24 kg/m² and overweight or obese ≥24 kg/m². Hazard ratios (HRs) and 95 % confidence intervals (95 %CIs) were estimated using the Cox proportional hazard model.

RESULTS

During over 30 years of follow-up we identified 654 incident esophageal squamous-cell carcinoma (ESCC) cases and 434 gastric cancer cases which included 88 gastric non-cardia carcinoma (GNCC) and 346 gastric cardia carcinoma (GCC) cases. Relative to normal weight, overweight or obesity were associated with a significantly reduced risk of ESCC (HR 0.69, 95 %CI 0.48-0.98) after multivariate adjustment, including age at baseline, gender, smoking, drinking, family history of cancer, education and consumption of fresh fruit. Subgroup analyses found that clear effects were evident in women and subjects with a family history of cancer. No association with gastric cancer was observed in any subjects or subgroups.

CONCLUSION

Overweight/obesity was associated with decreased risk of ESCC in this dysplasia population, particularly in women and persons who had a family history of cancer. Future studies are needed to confirm these findings.

Dietary Fat and Sugar in Promoting Cancer Development and Progression

The uncontrolled cellular growth that characterizes tumor formation requires a constant delivery of nutrients. Since the 1970s, researchers have wondered if the supply of nutrients from the diet could impact tumor development. Numerous studies have assessed the impact of dietary components, specifically sugar and fat, to increased cancer risk. For the most part, data from these trials have been inconclusive; however, this does not indicate that dietary factors do not contribute to cancer progression. Rather, the dietary contribution may be dependent on tumor, patient, and context, making it difficult to detect in the setting of large trials. In this review, we combine data from prospective cohort trials with mechanistic studies in mice to argue that fat and sugar can play a role in tumorigenesis and disease progression. We find that certain tumors may respond directly to dietary sugar (colorectal and endometrial cancers) and fat (prostate cancer) or indirectly to the obese state (breast cancer).

Aggregate penetrance of genomic variants for actionable disorders in European and African Americans

In populations that have not been selected for family history of disease, it is unclear how commonly pathogenic variants (PVs) in disease-associated genes for rare Mendelian conditions are found and how often they are associated with clinical features of these conditions. We conducted independent, prospective analyses of participants in two community-based epidemiological studies to test the hypothesis that persons carrying PVs in any of 56 genes that lead to 24 dominantly inherited, actionable conditions are more likely to exhibit the clinical features of the corresponding diseases than those without PVs. Among 462 European American Framingham Heart Study (FHS) and 3223 African-American Jackson Heart Study (JHS) participants who were exome-sequenced, we identified and classified 642 and 4429 unique variants, respectively, in these 56 genes while blinded to clinical data. In the same participants, we ascertained related clinical features from the participants' clinical history of cancer and most recent echocardiograms, electrocardiograms, and lipid measurements, without knowledge of variant classification. PVs were found in 5 FHS (1.1%) and 31 JHS (1.0%) participants. Carriers of PVs were more likely than expected, on the basis of incidence in noncarriers, to have related clinical features in both FHS (80.0% versus 12.4%) and JHS (26.9% versus 5.4%), yielding standardized incidence ratios of 6.4 [95% confidence interval (CI), 1.7 to 16.5; P = 7 × 10^-4) in FHS and 4.7 (95% CI, 1.9 to 9.7; P = 3 × 10^-4) in JHS. Individuals unselected for family history who carry PVs in 56 genes for actionable conditions have an increased aggregated risk of developing clinical features associated with the corresponding diseases.

Global and targeted serum metabolic profiling of colorectal cancer progression

BACKGROUND

Patients with colorectal adenoma polyps (PLPs) are at higher risk for developing colorectal cancer (CRC). However, the development of improved and robust biomarkers to enable the screening, surveillance, and early detection of PLPs and CRC continues to be a challenge. The aim of this study was to identify biomarkers of progression to CRC through metabolomic profiling of human serum samples with a multistage approach.

METHODS

Metabolomic profiling was conducted with the Metabolon platform for 30 CRC patients, 30 PLP patients, and 30 control subjects, and this was followed by the targeted validation of the top metabolites in an additional set of 50 CRC patients, 50 PLP patients, and 50 controls with liquid chromatography-tandem mass spectrometry. Unconditional multivariate logistic regression models, adjusted for covariates, were used to evaluate associations with PLP and CRC risk.

RESULTS

For the discovery phase, 404 serum metabolites were detected, with 50 metabolites showing differential levels between CRC patients, PLP patients, and controls (P for trend < .05). After validation, the 3 top metabolites (xanthine, hypoxanthine, and d-mannose) were validated: lower levels of xanthine and hypoxanthine and higher levels of d-mannose were found in PLP and CRC cases versus controls. A further exploratory analysis of metabolic pathways revealed key roles for the urea cycle and caffeine metabolism associated with PLP and CRC risk. In addition, a joint effect of the top metabolites with smoking and a significant interaction with the body mass index were observed. An analysis of the ratio of hypoxanthine levels to xanthine levels indicated an association with CRC progression.

CONCLUSIONS

These results suggest the potential utility of circulating metabolites as novel biomarkers for the early detection of CRC. Cancer 2017;123:4066-74. © 2017 American Cancer Society.

Carbohydrate nutrition and risk of adiposity-related cancers: results from the Framingham Offspring cohort (1991-2013)

Higher carbohydrate intake, glycaemic index (GI), and glycaemic load (GL) are hypothesised to increase cancer risk through metabolic dysregulation of the glucose-insulin axis and adiposity-related mechanisms, but epidemiological evidence is inconsistent. This prospective cohort study investigates carbohydrate quantity and quality in relation to risk of adiposity-related cancers, which represent the most commonly diagnosed preventable cancers in the USA. In exploratory analyses, associations with three site-specific cancers: breast, prostate and colorectal cancers were also examined. The study sample consisted of 3184 adults from the Framingham Offspring cohort. Dietary data were collected in 1991-1995 using a FFQ along with lifestyle and medical information. From 1991 to 2013, 565 incident adiposity-related cancers, including 124 breast, 157 prostate and sixty-eight colorectal cancers, were identified. Cox proportional hazards models were used to evaluate the role of carbohydrate nutrition in cancer risk. GI and GL were not associated with risk of adiposity-related cancers or any of the site-specific cancers. Total carbohydrate intake was not associated with risk of adiposity-related cancers combined or prostate and colorectal cancers. However, carbohydrate consumption in the highest v. lowest quintile was associated with 41 % lower breast cancer risk (hazard ratio (HR) 0·59; 95 % CI 0·36, 0·97). High-, medium- and low-GI foods were not associated with risk of adiposity-related cancers or prostate and colorectal cancers. In exploratory analyses, low-GI foods, were associated with 49 % lower breast cancer risk (HR 0·51; 95 % CI 0·32, 0·83). In this cohort of Caucasian American adults, associations between carbohydrate nutrition and cancer varied by cancer site. Healthier low-GI carbohydrate foods may prevent adiposity-related cancers among women, but these findings require confirmation in a larger sample.

Glucose and lipoprotein biomarkers and breast cancer severity using data from the Swedish AMORIS cohort

Background

The lipid and glucose metabolisms are postulated as possible intermediary mechanisms in linking obesity and breast cancer (BC). Links between serum lipid and glucose biomarkers and BC risk has been observed in the Swedish Apolipoprotein MORtality RISk (AMORIS) cohort. We conducted a follow-up analysis including information on tumour characteristics.

Methods

One thousand eight hundred twenty-four women diagnosed with BC, with serum biomarker levels of glucose, triglycerides, cholesterol (total, HDL, and LDL), and apolipoproteins A-1 and B recorded in a routine health check at baseline were included. BC severity was split into categories (good, moderate, and poor prognosis) based on ER status, TNM stage, and age at diagnosis. Proportional odds models were used to obtain odds ratios (ORs) and 95% confidence intervals (CI), with the interval time between baseline measurement and BC diagnosis accounted for.

Results

Serum glucose and the ApoB/ApoA-1 ratio showed a non-statistically significant positive association with BC severity (proportional OR: 1.25 (95%CI: 0.92–1.70) for glucose (</≥ 5.60 mmol/L) and 1.31 (95%CI: 0.97–1.76) for ApoB/A-1 ratio (</≥ 1). The proportion of severe and moderate BC was modestly greater across all abnormal serum biomarker groups.

Conclusions

Despite the size and detail of data in AMORIS, we only found a modest positive association between serum levels of glucose, apoB/ApoA-1 and BC severity, suggesting that these factors are not the main players in linking obesity and BC aggressiveness.

Electronic supplementary material

The online version of this article (doi:10.1186/s12885-017-3232-6) contains supplementary material, which is available to authorized users.

Prognostic value of glycated hemoglobin in colorectal cancer

AIM

To investigate the clinical significance of routinely used glycemic parameters in a cohort of colorectal cancer (CRC) patients.

METHODS

Pre-treatment fasting blood glucose, insulin, HbA_1c and homeostasis model of risk assessment (HOMA-IR) were retrospectively evaluated in a case-control study of 224 CRC and 112 control subjects matched for sex, obesity and diabetes frequency and blood lipid profile. Furthermore, the prognostic value of routinely used glycemic parameters towards progression-free (PFS) and overall survival (OS) was prospectively evaluated.

RESULTS

Fasting blood glucose, insulin, HOMA-IR and HbA_1c (all P < 0.0001) levels were higher in non-diabetic CRC patients compared with obesity-matched controls. All parameters were associated with increased CRC risk at ROC analysis, but no relationship with clinical-pathological variables or survival outcomes was observed for glycemia, insulinemia or HOMA-IR. Conversely, advanced CRC stage (P = 0.018) was an independent predictor of increased HbA_1c levels, which were also higher in patients who had disease progression compared with those who did not (P = 0.05). Elevated HbA_1c levels showed a negative prognostic value both in terms of PFS (HR = 1.24) and OS (HR = 1.36) after adjustment for major confounders, which was further confirmed in a subgroup analysis performed after exclusion of diabetic patients.

CONCLUSION

HbA_1c might have a negative prognostic value in CRC, thus suggesting that glycemic metabolic markers should be carefully monitored in these patients, independently of overt diabetes.

Insulin, insulin receptors, and cancer

Insulin is a major regulator of cell metabolism but, in addition, is also a growth factor. Insulin effects in target cells are mediated by the insulin receptor (IR), a transmembrane protein with enzymatic (tyrosine kinase) activity. The insulin receptor, however, is represented by a heterogeneous family of proteins, including two different IR isoforms and also hybrid receptors resulting from the IR hemireceptor combination with a hemireceptor of the cognate IGF-1 receptor. These different receptors may bind insulin and its analogs with different affinity and produce different biologic effects. Since many years, it is known that many cancer cells require insulin for optimal in vitro growth. Recent data indicate that: (1) insulin stimulates growth mainly via its own receptor and not the IGF-1 receptor; (2) in many cancer cells, the IR is overexpressed and the A isoform, which has a predominant mitogenic effect, is more represented than the B isoform. These characteristics provide a selective growth advantage to malignant cells when exposed to insulin. For this reason, all conditions of hyperinsulinemia, both endogenous (prediabetes, metabolic syndrome, obesity, type 2 diabetes before pancreas exhaustion and polycystic ovary syndrome) and exogenous (type 1 diabetes) will increase the risk of cancer. Cancer-related mortality is also increased in patients exposed to hyperinsulinemia but other factors, related to the different diseases, may also contribute. The complexity of the diseases associated with hyperinsulinemia and their therapies does not allow a precise evaluation of the cancer-promoting effect of hyperinsulinemia, but its detrimental effect on cancer incidence and mortality is well documented.

Diet-induced weight loss leads to a switch in gene regulatory network control in the rectal mucosa

BACKGROUND

Weight loss may decrease risk of colorectal cancer in obese individuals, yet its effect in the colorectum is not well understood. We used integrative network modeling, Passing Attributes between Networks for Data Assimilation, to estimate transcriptional regulatory network models from mRNA expression levels from rectal mucosa biopsies measured pre- and post-weight loss in 10 obese, pre-menopausal women.

RESULTS

We identified significantly greater regulatory targeting of glucose transport pathways in the post-weight loss regulatory network, including "regulation of glucose transport" (FDR=0.02), "hexose transport" (FDR=0.06), "glucose transport" (FDR=0.06) and "monosaccharide transport" (FDR=0.08). These findings were not evident by gene expression analysis alone. Network analysis also suggested a regulatory switch from NFΚB1 to MAX control of MYC post-weight loss.

CONCLUSIONS

These network-based results expand upon standard gene expression analysis by providing evidence for a potential mechanistic alteration caused by weight loss.

Pretreatment Insulin Levels as a Prognostic Factor for Breast Cancer Progression

BACKGROUND

Based on the hypothesis that impaired glucose metabolism might be associated with survival outcomes independently of overt diabetes, we sought to investigate the prognostic value of routinely used glycemic parameters in a prospective study of breast cancer (BC) patients.

PATIENTS AND METHODS

Fasting blood glucose, insulin and HbA1c levels, and insulin resistance (assessed by the Homeostasis Model Assessment [HOMA] index) at diagnosis were evaluated in 286 nondiabetic BC patients (249 with primary cancer, 37 with metastatic) with respect to those parameters' possible associations with clinicopathological features and survival outcomes. As a control group, 143 healthy women matched in a 2:1 ratio for age, blood lipid levels, and body mass index were also investigated.

RESULTS

Fasting blood glucose level (mean ± SD: 99 ± 26 vs. 85 ± 15 mg/dL), insulin level (median: 10.0 vs. 6.8 μIU/mL), and HOMA index (median: 2.2 vs. 1.4), but not HbA1c level, were significantly elevated in BC patients compared with control subjects. Receiver operating characteristics analysis showed comparable areas for blood glucose and insulin levels, and HOMA index (ranging from 0.668 to 0.671). Using a cutoff level of 13 μIU/mL, insulin had the best specificity (92%) and sensitivity (41%), was significantly associated with disease stage, and acted as a negative prognostic marker of progression-free survival (hazard ratio: 2.17; 95% confidence interval: 1.13-4.20) independently of menopausal status, disease stage, hormone receptor status, and human epidermal growth factor receptor 2 and Ki67 expression.

CONCLUSION

These results suggest that insulin determination might provide prognostic information in BC and support the hypothesis that lifestyle and/or pharmacological interventions targeting glucose metabolism could be considered to improve survival outcome of selected BC patients.

IMPLICATIONS FOR PRACTICE

Pretreatment insulin levels may represent a biomarker of adverse prognosis in nondiabetic women with breast cancer, independently of other well-established prognostic factors (i.e., stage, hormone receptors, HER2/neu, and Ki67). This finding has important implications, because it provides the rationale for lifestyle or insulin-targeting pharmacologic interventions as a means of improving breast cancer outcomes not only in early stages, but also in advanced-stage breast cancer patients with aggressive tumor phenotypes (HER2-negative hormone-resistant, or triple-negative breast cancer), in which treatments are still challenging. The possibility of using insulin as a biomarker to guide insulin-targeted interventions also should be taken into account.

Association between markers of glucose metabolism and risk of colorectal cancer

OBJECTIVES

Independent epidemiological studies have evaluated the association between markers of glucose metabolism (including fasting glucose, fasting insulin, homeostasis model of risk assessment-insulin resistance (HOMA-IR), glycated haemoglobin (HbA1c) and C peptide) and the risk of colorectal cancer (CRC). However, such associations have not been systematically analysed and no clear conclusions have been drawn. Therefore, we addressed this issue using a meta-analysis approach.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

PubMed and EMBASE were searched up to May 2015.

PRIMARY AND SECONDARY OUTCOME MEASURES

Either a fixed-effects or random-effects model was adopted to estimate overall ORs for the association between markers of glucose metabolism and the risk of CRC. In addition, dose-response, meta-regression, subgroup and publication bias analyses were conducted.

RESULTS

35 studies involving 25 566 patients and 5 706 361 participants were included. Higher levels of fasting glucose, fasting insulin, HOMA-IR, HbA1c and C peptide were all significantly associated with increased risk of CRC (fasting glucose, pooled OR=1.12, 95% CI 1.06 to 1.18; fasting insulin, pooled OR=1.42, 95% CI 1.19 to 1.69; HOMA-IR, pooled OR=1.47, 95% CI 1.24 to 1.74; HbA1c, pooled OR=1.22, 95% CI 1.02 to 1.47 (with borderline significance); C peptide, pooled OR=1.27, 95% CI 1.08 to 1.49). Subgroup analysis suggested that a higher HOMA-IR value was significantly associated with CRC risk in all subgroups, including gender, study design and geographic region. For the relative long-term markers, the association was significant for HbA1c in case-control studies, while C peptide was significantly associated with CRC risk in both the male group and colon cancer.

CONCLUSIONS

The real-time composite index HOMA-IR is a better indicator for CRC risk than are fasting glucose and fasting insulin. The relative long-term markers, HbA1c and C peptide, are also valid predictors for CRC risk. Considering the included case-control studies in the current analysis, more cohort studies are warranted to enhance future analysis.

A Linear Dose-Response Relationship between Fasting Plasma Glucose and Colorectal Cancer Risk: Systematic Review and Meta-analysis

For many years, the question of whether hyperglycaemia, a manifestation of prediabetes, diabetes mellitus and metabolic syndrome, is a risk factor for colorectal cancer has been intensely studied. In fact, even after the conclusion of several prospective studies, the topic is still controversial. We conducted a systematic review and meta-analysis to investigate the dose-response relationship between blood glucose concentration and the incidence of colorectal cancer. A linear (P = 0.303 for non-linearity) dose-response relationship was observed between fasting plasma glucose (FPG) and colorectal cancer risk without significant heterogeneity. The relative risk (RR) for colorectal cancer per 20 mg/dL increase in FPG was 1.015 (95% CI: 1.012-1.019, P = 0.000). In subgroup analyses, the pooled RRs for colon cancer (CC) and rectal cancer (RC) studies were 1.035 (95% CI 1.008-1.062, P = 0.011) and 1.031 (95% CI: 0.189-5.628, P = 0.972), respectively; in the analysis comparing men and women, the pooled RRs were 1.016 (95% CI: 1.012-1.020, P = 0.000) and 1.011 (95% CI: 0.995-1.027, P = 0.164), respectively. Sensitivity analyses using two methods showed similar results. In conclusion, there is a significant linear dose-response relationship between FPG and the incidence risk of colorectal cancer. For people with diabetes or prediabetes, controlling blood glucose might be useful to prevent colorectal cancer.

Metabolic serum biomarkers for the prediction of cancer: a follow-up of the studies conducted in the Swedish AMORIS study

The Swedish Apolipoprotein MOrtality RISk study (AMORIS) contains information on more than 500 biomarkers collected from 397,443 men and 414,630 women from the greater Stockholm area during the period 1985–1996. Using a ten-digit personal identification code, this database has been linked to Swedish national registries, which provide data on socioeconomic status, vital status, cancer diagnosis, comorbidity, and emigration. Within AMORIS, 18 studies assessing risk of overall and site-specific cancers have been published, utilising a range of serum markers representing glucose and lipid metabolism, immune system, iron metabolism, liver metabolism, and bone metabolism. This review briefly summarises these findings in relation to more recently published studies and provides an overview of where we are today and the challenges of observational studies when studying cancer risk prediction.

Overall, more recent observational studies supported previous findings obtained in AMORIS, although no new results have been reported for serum fructosamine and inorganic phosphate with respect to cancer risk. A drawback of using serum markers in predicting cancer risk is the potential fluctuations following other pathological conditions, resulting in non-specificity and imprecision of associations observed. Utilisation of multiple combination markers may provide more specificity, as well as give us repeated instead of single measurements. Associations with other diseases may also necessitate further analytical strategies addressing effects of serum markers on competing events in addition to cancer. Finally, delineating the role of serum metabolic markers may generate valuable information to complement emerging clinical studies on preventive effects of drugs and supplements targeting metabolic disorders against cancer.

Insulin receptor variants and obesity-related cancers in the Framingham Heart Study

PURPOSE

The insulin-signaling pathway plays a pivotal role in cancer biology; however, evidence of genetic alterations in human studies is limited. This case-control study nested within the Framingham Heart Study (FHS) examined the association between inherited genetic variation in the insulin receptor (INSR) gene and obesity-related cancer risk.

METHODS

The study sample consisted of 1,475 controls and 396 cases from the second familial generation of the FHS. Participants who provided consent were genotyped. Nineteen single-nucleotide polymorphisms (SNPs) in the INSR gene were investigated in relation to risk of obesity-related cancers combined and breast, prostate and colorectal cancers. Generalized estimation equation models controlling for familial correlations and include age, sex, smoking and body mass index as covariates, assuming additive models, were used.

RESULTS

Three SNPs, rs2059807, s8109559 and rs919275, were significantly associated with obesity-related cancers (p value < 0.02) with the most significantly associated SNP being rs2059807 (p value = 0.008). Carriers of two copies of SNP rs2059807 risk allele T were significantly less prevalent among subjects with obesity-related cancers [f(TT)cases = 14 vs. f(TT)controls = 18 %; OR 1.23]. In exploratory analyses evaluating site-specific cancers, the INSR rs2059807 association with these cancers was consistent with that observed for the main outcome (ORs colorectal cancer = 1.5, breast cancer = 1.29, prostate = 1.06). There was no statistically significant interaction between the INSR-SNP and blood glucose in relation to obesity-related cancer.

CONCLUSIONS

The INSR gene is implicated in obesity-related cancer risk, as 3 of 19 SNPs were nominally associated, after false discovery rate (FDR) correction, with the main outcome. Risk allele homozygotes (rs2059807) were less prevalent among subjects with obesity-related cancer. These results should be replicated in other populations to confirm the findings.

Prediabetes and the risk of cancer: a meta-analysis

AIMS/HYPOTHESIS

The results from prospective cohort studies of prediabetes (impaired fasting glucose and/or impaired glucose tolerance) and risk of cancer are controversial. We conducted a meta-analysis to evaluate the risk of cancer in association with impaired fasting glucose and impaired glucose tolerance.

METHODS

The PubMed, EMBASE and Cochrane Library databases were searched for prospective cohort studies with data on prediabetes and cancer. Two independent reviewers assessed the reports and extracted the data. Prospective studies were included if they reported adjusted RRs with 95% CIs for the association between cancer and prediabetes. Subgroup analyses were conducted according to endpoint, age, sex, ethnicity, duration of follow-up and study characteristics.

RESULTS

Data from 891,426 participants were derived from 16 prospective cohort studies. Prediabetes was associated with an increased risk of cancer overall (RR 1.15; 95% CI 1.06, 1.23). The results were consistent across cancer endpoint, age, duration of follow-up and ethnicity. There was no significant difference for the risk of cancer with different definitions of prediabetes. In a site-specific cancer analysis, prediabetes was significantly associated with increased risks of cancer of the stomach/colorectum, liver, pancreas, breast and endometrium (all p < 0.05), but not associated with cancer of the bronchus/lung, prostate, ovary, kidney or bladder. The risks of site-specific cancer were significantly different (p = 0.01) and were highest for liver, endometrial and stomach/colorectal cancer.

CONCLUSIONS/INTERPRETATION

Overall, prediabetes was associated with an increased risk of cancer, especially liver, endometrial and stomach/colorectal cancer.

Association between fasting serum glucose levels and incidence of colorectal cancer in Korean men: the Korean Cancer Prevention Study-II

INTRODUCTION

The incidence of colorectal cancer (CRC) is steadily increasing worldwide. Numerous studies have demonstrated that diabetes mellitus is related to an increased risk of CRC; however, the association between impaired fasting glucose and CRC is unclear. Therefore, we evaluated the correlation between fasting serum glucose (FSG) levels and the incidence of CRC, which can be used to develop novel methods for preventing CRC.

METHODS

A total of 175,677 individuals from the Korean Metabolic Syndrome Research Initiative study were enrolled between 2004 and 2011. The incidence of CRC was assessed during a mean follow-up of 4.7 years. Hazard ratios (HR) for CRC according to FSG levels were calculated with the Cox proportional hazard model adjusted for age, sex, body mass index, smoking status, alcohol consumption, and regular exercise.

RESULTS

The risk of developing CRC in subjects with high FSG was significant (HR, 1.45; 95% confidence interval [CI], 1.10-1.90), and the risk was higher in men (HR, 1.51; 95% CI, 1.12-2.05). The HR of rectal cancer, but not colon cancer, was significantly higher both in the total population and in men in the high FSG group.

CONCLUSIONS

The incidence of CRC positively correlated with FSG levels in men. Rectal cancer incidence was especially correlated with high FSG in the site-specific analysis. Therefore, serum glucose levels maybe a potential marker of colorectal cancer. Early detection and intervention for controlling elevated glucose levels may be indicated as a way to prevent carcinogenesis.

Metabolic health reduces risk of obesity-related cancer in framingham study adults

BACKGROUND

It is unknown whether the risk for obesity-related cancers differs between metabolically unhealthy and healthy overweight/obese adults.

METHODS

Data on body mass index (BMI), waist circumference (WC), waist-to-height ratio (WHtR), and random blood glucose in Framingham Heart Study adults (n = 3,763) ages 55 to 69 years were used to estimate risks of obesity-related cancers (n = 385), including postmenopausal breast, female reproductive, colon, liver, gallbladder, pancreas, and kidney cancers, as well as esophageal adenocarcinomas. Multivariable-adjusted Cox proportional hazards models were used to estimate risk for obesity-related cancers associated with body fat and metabolic health (as defined by glucose levels) among subjects in three risk groups (vs. referent group with normal weight/normal glucose): normal weight/elevated glucose, overweight/normal glucose, and overweight/elevated glucose.

RESULTS

Overweight adults [BMI ≥ 25 or WHtR ≥ 0.51 (men) and ≥0.57 (women)] with elevated glucose (≥125 mg/dL) had a statistically significant 2-fold increased risk of developing obesity-related cancer, whereas overweight adults with normal glucose had a 50% increased risk. Normal-weight adults with elevated glucose had no excess cancer risk. The effects of BMI and WHtR were independent of one another. Finally, overweight women with elevated blood glucose had a 2.6-fold increased risk [95% confidence interval (CI), 1.4-4.9] of female reproductive (cervical, endometrial, uterine cancers) and postmenopausal breast cancers, whereas overweight women with normal glucose levels had only a 70% increased risk (95% CI, 1.1-2.5).

CONCLUSION

These results suggest that cancer risk may be lower among metabolically healthy overweight/obese older adults than among overweight/obese adults with metabolic dysfunction.

IMPACT

Metabolic dysfunction and obesity act synergistically to increase cancer risk.

Cellular metabolism in colorectal carcinogenesis: Influence of lifestyle, gut microbiome and metabolic pathways

The interconnectivity between diet, gut microbiota and cell molecular responses is well known; however, only recently has technology allowed the identification of strains of microorganisms harbored in the gastrointestinal tract that may increase susceptibility to cancer. The colonic environment appears to play a role in the development of colon cancer, which is influenced by the human metabolic lifestyle and changes in the gut microbiome. Studying metabolic changes at the cellular level in cancer be useful for developing novel improved preventative measures, such as screening through metabolic breath-tests or treatment options that directly affect the metabolic pathways responsible for the carcinogenicity.