Fasting serum insulin levels and insulin resistance are associated with colorectal adenoma in Koreans

Comparison of some biochemical markers between early‐onset and late‐onset colorectal precancerous lesions: A single‐center retrospective study

Objective

Given that the onset of diseases including colorectal cancer precursors is affecting younger individuals and that obesity is an important risk factor for early‐onset, we conducted a study to explore the biochemical profile of differences in serum between early‐onset patients and late‐onset colorectal precancerous lesions.

Methods

A total of 1447 patients, including 469 early‐onset patients and 978 late‐onset patients, were enrolled from the First Affiliated Hospital of Nanchang University (FAHNU), of which there were 311 sessile serrated adenoma/polyps (SSA/P) and 1136 normal adenomas. The distribution of the included categorical variables was compared via Pearson's chi‐squared test, whereas continuous variables were compared by using the nonparametric Kruskal–Wallis test and anova.

Results

Compared with late‐onset patients, the levels of total bilirubin and HDL‐C were lower (p < 0.05), whereas triglyceride and uric acid levels were higher, in early‐onset patients. Interestingly, in the subgroup analysis, triglyceride and uric acid levels remained at higher levels, whereas HDL‐C remained at lower levels, in early‐onset patients than in late‐onset patients. Other characteristics, such as LDL‐C, drinking, γ‐GT, and the N/L ratio, were similar between the two groups. An additional analysis of the association of tumor size with markers showed that lower levels of HDL‐C and higher levels of uric acid were associated with increased tumor size (p < 0.05).

Conclusions

Early‐onset CRC precursor cases exhibit higher levels of triglycerides and lower levels of HDL‐C than late‐onset cases. Additionally, levels of HDL‐C are negatively associated with tumor size, whereas uric acid was positively correlated with tumor size.

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.

Hyperinsulinemia, insulin resistance and colorectal adenomas: A meta-analysis

BACKGROUND

Insulin stimulates cell proliferation and inhibits apoptosis. While epidemiologic studies have investigated associations between markers of insulin resistance/hyperinsulinemia (i.e., circulating insulin, homeostasis model assessment-insulin resistance (HOMA-IR), C-peptide) and risk of colorectal adenoma (CRA), the effect size has not yet been quantified.

OBJECTIVE

We aimed to summarize the association between hyperinsulinemia/insulin resistance and risk of CRA, including whether the association is independent of adiposity.

MATERIALS AND METHODS

Pubmed and Embase were searched through April, 2015 to identify observational studies investigating the associations between insulin, C-peptide and HOMA-IR and CRA risk. Using the highest versus lowest category meta-analysis and dose-response meta-analysis based on a random-effects model, we estimated summary odds ratio (OR) and the corresponding 95% confidence interval (95% CI).

RESULTS

A total of 27 studies (insulin: 16 studies including 14,007 cases; C-peptide: 11 studies including 8639 cases; HOMA-IR: 8 studies including 11,619 cases) were included in this meta-analysis. The summary ORs of CRA comparing the highest with the lowest quantile were 1.33 for insulin (95% CI=1.12-1.58, I(2)=73.9%, Pheterogeneity<0.001), 1.44 for C-peptide (95% CI=1.13-1.83, I(2)=63.5%, Pheterogeneity=0.003), and 1.33 for HOMA-IR (95% CI=1.10-1.60, I(2)=69.1%, Pheterogeneity=0.004). Upon stratification by ethnicity, higher levels of insulin and C-peptide were significantly associated with increased risk of CRA in non-Asian ethnicity (summary OR for insulin=1.67 [95% CI=1.28-2.17], I(2)=34.9%, Pheterogeneity=0.16; summary OR for C-peptide=1.59 [95% CI=1.22-2.08], I(2)=21.5%, Pheterogeneity=0.27) but not in Asians (summary OR for insulin=1.10 [95% CI=0.92-1.33], I(2)=76.6%, Pheterogeneity=0.001; summary OR for C-peptide=1.27 [95% CI=0.84-1.91], I(2)=72.6, Pheterogeneity=0.01). We observed evidence for the existence of publication bias for insulin (P=0.01 by Egger test) and HOMA-IR (P=0.05 by Egger test). The results were confirmed in linear dose-response meta-analysis. These significant positive associations generally persisted even after adjustment for adiposity, although the effect size was substantially attenuated.

CONCLUSIONS

Independent of adiposity, higher levels of insulin, C-peptide, and HOMA-IR were significantly associated with increased risk of CRA. The weaker associations and high heterogeneity in Asian studies warrant further research. These results indicate that insulin resistance and hyperinsulinemia may contribute in part to the association between obesity and CRA risk.

Association between nonalcoholic fatty liver disease and colorectal adenoma: a systematic review and meta-analysis

BACKGROUND AND AIMS

Several existing studies indicated that nonalcoholic fatty liver disease (NAFLD) may be associated with colorectal adenoma, but the results and risk factors are controversial. A systematic review of studies was conducted to explore these issues by meta-analysis.

METHODS

We searched the Pubmed, Embase, Cochrane library, Medline and Web of Science databases for studies published before May 30(th), 2014. A statistical analysis was performed using RevMan 5.2 software.

RESULTS

Seven studies involving 11,905 participants from different regions were included. Among them, five trials carried out subgroup of NAFLD patients in colorectal adenoma population. The result showed NAFLD was significantly correlated with adenoma of colon (Odds ratio [OR] = 1.56, 95% confidence interval [CI]: 1.22-1.99, P = 0.0003). It could be found in stratified analysis that patients had more chance to get multiple adenomas when they suffered NAFLD (Rate ratio [RR]: 1.52, 95% CI: 1.08-2.13, P = 0.02). Such risk factors of NAFLD as age, waist circumference, body mass index (BMI), disorder of lipid metabolism, hyperglycemia and high blood pressure (HBP) increased risk of colorectal adenoma (Age: mean difference [MD]: 2.81, 95% CI: 0.33-5.28; Waist: MD: 2.84, 95% CI: 2.14-3.54; BMI: MD: 0.85, 95% CI: 0.69-1.01; High-density lipoprotein: MD: -2.46, 95% CI: -3.68 to -1.24; Triglyceride: MD: 16.12, 95% CI: 8.89-23.36; Low-density lipoprotein: MD: 6.04, 95% CI: 3.60-8.48; Cholesterol: MD: 4.25, 95% CI: 0.87-7.63; Fasting glucose: MD: 2.27, 95% CI: 1.24-3.30; HBP: OR = 1.51, 95% CI: 1.22-1.88), while diabetes had no significant association with it (OR = 1.43, 95% CI: 0.94-2.17, P = 0.09). Besides, NAFLD didn't affect the location, size and advanced type of colorectal adenoma (P > 0.05).

CONCLUSION

The present systematic review and meta-analysis demonstrated NAFLD was closely associated with great risk of colorectal adenoma and its number, but not with its location, size and advanced type. Waist, obesity, lipid profiles, glucose, hypertension played roles in the process of colorectal adenoma.

Fasting serum insulin levels and insulin resistance are associated with colorectal adenoma in Koreans

AIMS/INTRODUCTION

Insulin has been associated with the risk of colorectal cancer (CRC). However, few studies have evaluated the association between insulin and colorectal adenoma. We investigated the relationship between fasting serum insulin levels or homeostasis model assessment of insulin resistance (HOMA-IR) and colorectal adenoma.

MATERIALS AND METHODS

We retrospectively enrolled 15,427 participants who underwent both fasting serum insulin measurement and colonoscopy for a routine health examination at Asan Medical Center from January 2007 to December 2008. Participants with a history of any cancer, previous colectomy or polypectomy, those taking antidiabetic medications, and inflammatory bowel disease, non-specific colitis, non-adenomatous polyps only or CRC on colonoscopic findings were excluded. Finally, 3,606 participants with histologically confirmed colorectal adenoma and 6,019 controls with no abnormal findings on colonoscopy were included. Participants were categorized into quartiles (Q) based on fasting serum insulin levels and HOMA-IR.

RESULTS

Fasting serum insulin and HOMA-IR were significantly higher in participants with colorectal adenomas compared with controls. Multivariate regression analysis adjusting for age, sex, smoking habits, drinking habits and family history of CRC showed that participants with higher quartiles of fasting serum insulin levels (odd ratio [OR] 1.17 for 2nd Q, 1.19 for 3rd Q, and 1.42 for 4th Q, P < 0.05) or HOMA-IR (OR 1.18 for 2nd Q and 1.45 for 4th Q, P < 0.05) showed significantly increased ORs of colorectal adenoma compared with the lowest quartiles.

CONCLUSIONS

These findings showed that increased serum insulin levels and insulin resistance were significantly associated with the presence of colorectal adenoma.