Association of fasting serum insulin and cancer mortality in a healthy population - 28-year follow-up of the French TELECOM Study

Insulin Resistance: The Increased Risk of Cancers

Insulin resistance, also known as impaired insulin sensitivity, is the result of a decreased reaction of insulin signaling to blood glucose levels. This state is observed when muscle cells, adipose tissue, and liver cells, improperly respond to a particular concentration of insulin. Insulin resistance and related increased plasma insulin levels (hyperinsulinemia) may cause metabolic impairments, which are pathological states observed in obesity and type 2 diabetes mellitus. Observations of cancer patients confirm that hyperinsulinemia is a major factor influencing obesity, type 2 diabetes, and cancer. Obesity and diabetes have been reported as risks of the initiation, progression, and metastasis of several cancers. However, both of the aforementioned pathologies may independently and additionally increase the cancer risk. The state of metabolic disorders observed in cancer patients is associated with poor outcomes of cancer treatment. For example, patients suffering from metabolic disorders have higher cancer recurrence rates and their overall survival is reduced. In these associations between insulin resistance and cancer risk, an overview of the various pathogenic mechanisms that play a role in the development of cancer is discussed.

The Association of Empirical Dietary Index for Hyperinsulinemia with the Risk of Cancer and Cancer Mortality: A Meta-analysis of Observational Studies

This meta-analysis aimed to assess the association between the empirical dietary index for hyperinsulinemia (EDIH) and cancer mortality risk. We performed a comprehensive search across the online literature up to November 2022 databases. Then, hazard ratio (H.R.) and 95% confidence intervals (CI) were extracted. A total of 14 and seven cohort studies that reported H.R. for the risk of cancer incidence and cancer mortality respectively were included. The pooled H.R. (95% CI) of the association between EDIH and cancer incidence was 1.13 (1.05-1.23) in overall meta-analyses, 1.15 (1.08-1.22) in female subgroups, 1.27 (1.14-1.41) in digestive cancer subgroups, and 1.15 (1.07-1.24) in breast cancer subgroups. Also, the pooled H.R. (95% CI) of the association between EDIH and incidence of cancer mortality was 1.19 (1.13-1.26) in overall meta-analyses, 1.23 (1.13-1.34) in males, 1.18(1.10-1.28) in females, and 1.20 (1.13-1.27) in studies conducted on all cancers as an outcome. Our findings revealed that a higher EDIH was significantly associated with an increased risk of cancer incidence, particularly in females, digestive cancers, and breast cancer. Also, a higher EDIH score was related to a higher risk of cancer mortality overall in both male and female subgroups and with all cancers.

Bidirectional Mendelian randomization study of insulin-related traits and risk of ovarian cancer

BACKGROUND

It is well known that the occurrence and development of ovarian cancer are closely related to the patient's weight and various endocrine factors in the body.

AIM

Mendelian randomization (MR) was used to analyze the bidirectional relationship between insulin related characteristics and ovarian cancer.

METHODS

The data on insulin related characteristics are from up to 5567 diabetes free patients from 10 studies, mainly including fasting insulin level, insulin secretion rate, peak insulin response, etc. For ovarian cancer, UK Biobank data just updated in 2021 was selected, of which the relevant gene data was from 199741 Europeans. Mendelian randomization method was selected, with inverse variance weighting (IVW) as the main estimation, while MR Pleiotropy, MR Egger, weighted median and other methods were used to detect the heterogeneity of data and whether there was multi validity affecting conclusions.

RESULTS

Among all insulin related indicators (fasting insulin level, insulin secretion rate, peak insulin response), the insulin secretion rate was selected to have a causal relationship with the occurrence of ovarian cancer (IVW, P < 0.05), that is, the risk of ovarian cancer increased with the decrease of insulin secretion rate. At the same time, we tested the heterogeneity and polymorphism of this indicator, and the results were non-existent, which ensured the accuracy of the analysis results. Reverse causal analysis showed that there was no causal effect between the two (P>0.05).

CONCLUSION

The impairment of the insulin secretion rate has a causal effect on the risk of ovarian cancer, which was confirmed by Mendel randomization. This suggests that the human glucose metabolism cycle represented by insulin secretion plays an important role in the pathogenesis of ovarian cancer, which provides a new idea for preventing the release of ovarian cancer.

Are U-shaped relationships between risk factors and outcomes artifactual?

BACKGROUND

The objective of this study was to evaluate whether the observed nadir in a U- or J-shaped relationship between a particular risk factor and a future health outcome is a function of the distribution of the risk factor in the sample being analyzed.

METHODS

Data from the ORIGIN trial were used to assess the relationship between three risk factors (weight, systolic blood pressure, and serum insulin) and the hazard of a major cardiovascular event comprising a nonfatal myocardial infarction, nonfatal stroke, or cardiovascular death. Three spline curves were generated for each risk factor. The first was based on all available data, the second for a subgroup with a higher mean risk factor level, and the third for a subgroup with a lower mean risk factor level. Nadir levels of the risk factor (i.e., risk factor levels predicting the lowest hazard) were then identified for each spline curve.

RESULTS

When compared to the nadir values based on all available data, nadir values for all three risk factors were higher for the subgroups with higher mean levels and lower for those with lower mean levels.

CONCLUSIONS

The distribution of a risk factor in the population is an important determinant of its nadir value. Populations with high or low values may have high and low nadirs, respectively. Identification of a nadir for a modifiable risk factor from epidemiologic relationships may therefore arise from this distribution bias and is therefore unrelated to therapeutic targets.

Diets with higher insulinaemic potential are associated with increased risk of overall and cardiovascular disease-specific mortality

Hyperinsulinaemia and insulin resistance have been proposed to be associated with mortality risk, and diet can modulate insulin response. However, whether dietary patterns with high insulinaemic potential are associated with mortality remains unknown. We prospectively examined the associations between hyperinsulinaemic diets and the risk of total and cause-specific mortality in a large nationally representative population. Dietary factors were assessed by 24-h recalls. Two empirical dietary indices for hyperinsulinaemia (EDIH) and insulin resistance (EDIR) were developed to identify food groups most predictive of biomarkers for hyperinsulinaemia (C-peptide and insulin) and insulin resistance (homoeostatic model assessment for insulin resistance), respectively. Deaths from date of the first dietary interview until 31 December 2015 were identified by the National Death Index. Multivariable hazard ratios (HR) and 95 % CI were calculated using Cox regression models. During a median follow-up of 7·8 years, 4904 deaths were documented among 40 074 participants. For EDIH, the multivariable-adjusted HR (comparing extreme quintiles) were 1·20 (95 % CI 1·09, 1·32, P-trend<0·001) for overall mortality and 1·41 (95 % CI 1·15, 1·74, P-trend = 0·002) for CVD mortality. Similar associations were observed for EDIR with HR of 1·18 (95 % CI 1·07, 1·29, P-trend < 0·001) for total and 1·35 (95 % CI 1·09, 1·67, P-trend = 0·005) for CVD mortality. After further adjustments for BMI and diabetes, these positive associations were somewhat attenuated. Our findings suggested that diets with higher insulinaemic potential are associated with increased risk of overall and CVD-specific mortality.

Obesity, cancer risk, and time-restricted eating

Obesity and the associated metabolic syndrome is considered a pandemic whose prevalence is steadily increasing in many countries worldwide. It is a complex, dynamic, and multifactorial disorder that presages the development of several metabolic, cardiovascular, and neurodegenerative diseases, and increases the risk of cancer. In patients with newly diagnosed cancer, obesity worsens prognosis, increasing the risk of recurrence and decreasing survival. The multiple negative effects of obesity on cancer outcomes are substantial, and of great clinical importance. Strategies for weight control have potential utility for both prevention efforts and enhancing cancer outcomes. Presently, time-restricted eating (TRE) is a popular dietary intervention that involves limiting the consumption of calories to a specific window of time without any proscribed caloric restriction or alteration in dietary composition. As such, TRE is a sustainable long-term behavioral modification, when compared to other dietary interventions, and has shown many health benefits in animals and humans. The preliminary data regarding the effects of time-restricted feeding on cancer development and growth in animal models are promising but studies in humans are lacking. Interestingly, several short-term randomized clinical trials of TRE have shown favorable effects to reduce cancer risk factors; however, long-term trials of TRE have yet to investigate reductions in cancer incidence or outcomes in the general population. Few studies have been conducted in cancer populations, but a number are underway to examine the effect of TRE on cancer biology and recurrence. Given the simplicity, feasibility, and favorable metabolic improvements elicited by TRE in obese men and women, TRE may be useful in obese cancer patients and cancer survivors; however, the clinical implementation of TRE in the cancer setting will require greater in-depth investigation.

Insulin and cancer: a tangled web

For a century, since the pioneering work of Otto Warburg, the interwoven relationship between metabolism and cancer has been appreciated. More recently, with obesity rates rising in the U.S. and worldwide, epidemiologic evidence has supported a link between obesity and cancer. A substantial body of work seeks to mechanistically unpack the association between obesity, altered metabolism, and cancer. Without question, these relationships are multifactorial and cannot be distilled to a single obesity- and metabolism-altering hormone, substrate, or factor. However, it is important to understand the hormone-specific associations between metabolism and cancer. Here, we review the links between obesity, metabolic dysregulation, insulin, and cancer, with an emphasis on current investigational metabolic adjuncts to standard-of-care cancer treatment.

The association of dietary insulin load and index with the risk of cancer and cancer mortality: a systematic review and meta-analysis

Purpose

Insulin levels play an important role in cancer development. However, the link between an insulinogenic diet and cancer is still unclear. Therefore, we performed a systematic review with meta-analysis to investigate the association between dietary insulin index (II) and load (IL) with cancer risk and mortality.

Methods

A comprehensive search between electronic databases (Web of Science, PubMed/Medline, Scopus, and Google Scholar) was conducted to identify relevant studies up to January 2022. The relative risks (RR) and Odds ratios (OR) were extracted from eligible studies, and meta-analysis was performed to calculate the pooled effect size.

Result

12 papers including 14 studies (10 cohorts and 4 case-control) were included for the meta-analysis. Among them, 10 studies reported effect size for the risk of cancer, and 4 studies reported effect size for cancer mortality. We observed no significant association between II and IL with cancer overall (RR_II: 1.03, 95%CI: 0.91-1.17, RR_IL: 1.16, 95%CI: 0.94-1.42) and in cohort studies, however, in case-control studies was related with higher odds of cancer (OR_II: 2.30, 95%CI: 1.21-4.38, OR_IL: 2.57, 95%CI: 1.64-4.02). Higher II and IL scores were associated with the increased risk of total (RR_II: 1.29, 95%CI: 1.02-1.63) and (RR_IL: 1.39, 95%CI: 1.06-1.83) and colorectal cancer mortality (RR_II: 1.29, 95%CI: 1.13-1.48) and (RR_IL: 1.37, 95%CI: 1.18-1.60).

Conclusion

Higher dietary II and IL were not associated with cancer risk in overall and cohort studies, whereas related with a higher risk of cancer in case-control studies. We observed a significant positive relation of II and IL with cancer mortality, especially CRC mortality.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-022-01013-3.

Dietary Insulinemic Potential and Risk of Total and Cause-Specific Mortality in the Nurses' Health Study and the Health Professionals Follow-up Study

OBJECTIVE

Insulin response is related to overall health. Diet modulates insulin response. We investigated whether insulinemic potential of diet is associated with risk of all-cause and cause-specific mortality.

RESEARCH DESIGN AND METHODS

We prospectively followed 63,464 women from the Nurses' Health Study (1986-2016) and 42,880 men from the Health Professionals Follow-up Study (1986-2016). Diet was assessed by food frequency questionnaires every 4 years. The insulinemic potential of diet was evaluated using a food-based empirical dietary index for hyperinsulinemia (EDIH), which was predefined based on predicting circulating C-peptide concentrations.

RESULTS

During 2,792,550 person-years of follow-up, 38,329 deaths occurred. In the pooled multivariable-adjusted analyses, a higher dietary insulinemic potential was associated with an increased risk of mortality from all-cause (hazard ratio [HR] comparing extreme quintiles: 1.33; 95% CI 1.29, 1.38; P-trend <0.001), cardiovascular disease (CVD) (HR 1.37; 95% CI 1.27, 1.46; P-trend <0.001), and cancers (HR 1.20; 95% CI 1.13, 1.28; P-trend <0.001). These associations were independent of BMI and remained significant after further adjustment for other well-known dietary indices. Furthermore, compared with participants whose EDIH scores were stable over an 8-year period, those with the greatest increases had a higher subsequent risk of all-cause (HR 1.13; 95% CI 1.09, 1.18; P-trend <0.001) and CVD (HR 1.10; 95% CI 1.01, 1.21; P-trend = 0.006) mortality.

CONCLUSIONS

Higher insulinemic potential of diet was associated with increased risk of all-cause, CVD, and cancer mortality. Adopting a diet with low insulinemic potential might be an effective approach to improve overall health and prevent premature death.

Fasting Insulin and Risk of Overall and 14 Site-Specific Cancers: Evidence From Genetic Data

Objective

Whether fasting insulin (FI) plays a role in cancer risk remains unclear. This study aimed to investigate the association between FI and cancer risk and to explore its potential mediator role in the association between type 2 diabetes mellitus (T2DM) and cancer.

Methods

Two-sample Mendelian randomization (TSMR) analysis was performed to evaluate the effect of FI on overall and 14 site-specific cancers using genome-wide association study (GWAS) summary-level data from Meta-Analyses of Glucose and Insulin-related traits Consortium (MAGIC) and consortia of 14 site-specific cancers. The primary MR approach was conducted by using the random-effect inverse-variance weighted (IVW) method, and sensitivity analyses were implemented by adopting weighted-median, weighted-mode, MR-Egger, and MR-PRESSO tests. Polygenic risk score analysis was executed by using individual-level data from UK Biobank to validate the findings from TSMR analyses. Multivariable Mendelian randomization (MVMR) was carried out to estimate the mediation effect of FI on the association between T2DM and cancer.

Results

TSMR study suggested that genetically determined high FI levels were associated with increased risk of colorectal cancer (odds ratio (OR) = 1.87, 95% CI: 1.23-2.84, p = 0.003) and endometrial cancer (OR = 1.89, 95% CI: 1.08-3.01, p = 0.008), but not associated with overall cancer risk or the other 12 studied cancer sites. Polygenic risk score analysis successfully replicated the association between genetic liability to high FI levels and the increased risk of colorectal and endometrial cancers. MVMR and MR mediation analyses detected an intermediary effect of FI and quantified that FI mediated 21.3% of the association between T2DM and endometrial cancer.

Conclusions

This study demonstrated that FI levels are associated with the risk of colorectal and endometrial cancers, and FI was found to play an intermediary role in the association between T2DM and endometrial cancer. The associations between FI and other cancers need to be further studied.

Insulin Resistance and Cancer-Specific and All-Cause Mortality in Postmenopausal Women: The Women's Health Initiative

BACKGROUND

Insulin resistance has been proposed as a mediator of the increased cancer incidence and mortality associated with obesity. However, prior studies included limited cancer deaths and had inconsistent findings. Therefore, we evaluated insulin resistance and cancer-specific and all-cause mortality in postmenopausal women participating in the Women's Health Initiative (WHI).

METHODS

Eligible were a subsample of 22 837 WHI participants aged 50-79 years enrolled at 40 US clinical centers from 1993 to 1998 who had baseline fasting glucose and insulin levels. Baseline insulin resistance was measured by the homeostasis model assessment of insulin resistance (HOMA-IR). Cancers were verified by central medical record review and deaths verified by medical record and death certificate review enhanced by National Death Index queries. Cox proportional hazards regression models were used to calculate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for cancer-specific and all-cause mortality. All statistical tests were two-sided.

RESULTS

During a median of 18.9 years of follow-up, 1820 cancer deaths and 7415 total deaths occurred. Higher HOMA-IR quartile was associated with higher cancer-specific mortality (Q4 vs Q1, HR = 1.26, 95% CI = 1.09 to 1.47; Ptrend = .003) and all-cause mortality (Q4 vs Q1, HR = 1.63, 95% CI = 1.51 to 1.76; Ptrend < .001). A sensitivity analysis for diabetes status did not change findings. Among women with body mass index less than 25 kg/m2, higher HOMA-IR quartile was associated with higher cancer mortality (Fine and Gray, P = .004).

CONCLUSIONS

High insulin resistance, as measured by HOMA-IR, identifies postmenopausal women at higher risk for cancer-specific and all-cause mortality who could potentially benefit from early intervention.

Fasting Insulin and Risk of Cancer Related Mortality in Non-diabetic Adults: A Dose-response Meta-analysis of Cohort Studies

BACKGROUND

Insulin is known to have direct and indirect effects on cell cycle progression, proliferation and metastatic activities. We performed a dose-response meta-analysis to investigate the association between hyperinsulinemia and all-cause cancer related mortality.

METHODS

A systematic literature search was conducted on MEDLINE and SCOPUS databases to include all published articles up to January 2019. Combined hazard ratios (HRs) with 95% Confidence Intervals (CIs) were estimated using DerSimonian and Laird random-effects models. A dose-response analysis was also conducted to further explore insulin's relationship with cancer-related mortality.

RESULTS

We identified seven studies, with a total of 23,990 participants, who reported the association between hyperinsulinemia and cancer-related mortality. Results from the eligible studies indicated that higher fasting insulin levels were not associated with an increased risk of cancer mortality (pooled HR: 1.14, 95% CI: 0.99-1.32), however, significant heterogeneity was present (I2 = 60.3%, P heterogeneity = 0.001). A subgroup analysis based on gender demonstrated a significant association between fasting insulin level and cancer mortality in men (pooled HR: 1.92, 95% CI: 1.23-3.01, P heterogeneity = 0.281).

CONCLUSION

This dose-response meta-analysis showed a direct significant association between fasting insulin level and cancer mortality in men.

PFKFB3, a key glucose metabolic enzyme regulated by pathogen recognition receptor TLR4 in liver cells

AIMS

Toll-like receptor 4 (TLR4) and 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase (PFKFB3) are involved in the progress of inflammation and glucose metabolism. Here, we aimed to assess the relationship between TLR4 and PFKFB3 in liver cells.

METHODS

We detected the expression of TLR4 and PFKFB3 in both normal liver cell lines and liver cancer cell lines. Then, a small interfering RNA (siRNA) was used to knock down the expression of TLR4 and analyze the expression of PFKFB3 in the HL-7702 cell line. Further, following stimulation of the HL-7702 cell line with free fatty acids (FFA) or insulin, we observed the expression of TLR4 and PFKFB3, respectively.

RESULTS

Knocking down siRNA-mediated TLR4 significantly reduced PFKFB3 expression at the mRNA and protein level. Furthermore, activating TLR4 with FFA dramatically increased PFKFB3 expression. Insulin increased the expression of TLR4 and PFKFB3, which could be inhibited by TLR siRNA.

CONCLUSION

These findings suggest that PFKFB3 expression is regulated via the TLR4-PFKFB3 axis, which might be a bridge linking fat and glucose metabolism.

Dose-response effects of exercise on insulin among colon cancer survivors

Physical activity is associated with a lower risk of disease recurrence among colon cancer survivors. The pathways through which physical activity may alter disease outcomes are unknown, but may include changes in metabolic growth factors, such as insulin. Between January 2015 and August 2015, 39 stage I-III colon cancer survivors were randomized to one of the three groups: usual care control, 150 min/week of aerobic exercise (low-dose) and 300 min/week of aerobic exercise (high-dose) for six months. The pre-specified key metabolic growth factor outcome was fasting insulin. Insulin resistance was quantified using the homeostatic model assessment. Mean age was 56.5 ± 10.0 years, 51% had stage III disease, 72% were treated with chemotherapy and the mean time since finishing treatment was 10.9 ± 6.1 months. Over six months, the low-dose group completed 141.5 ± 9.9 min/week of aerobic exercise, and the high-dose group completed 247.2 ± 10.7 min/week of aerobic exercise. Fasting insulin concentrations decreased 7.4 ± 9.4 pmol/L in the control group, 28.0 ± 8.3 pmol/L in the low-dose group and 20.7 ± 9.3 pmol/L in the high-dose group (nonlinear Ptrend = 0.042). Insulin resistance decreased 0.11 ± 0.20 in the control group, 0.63 ± 0.17 in the low-dose group and 0.43 ± 0.19 in the high-dose group (nonlinear Ptrend = 0.012). Aerobic exercise reduces insulin concentrations and insulin resistance among patients with stage I-III colon cancer. Prescribing 150 min/week of aerobic exercise may be sufficient for reducing insulin concentrations and insulin resistance, which may partially mediate the relationship between physical activity and colon cancer prognosis.