Racial differences in the association of insulin-like growth factor pathway and colorectal adenoma risk

Association between greater leg length and increased incidence of colorectal cancer: the atherosclerosis risk in communities (ARIC) study

PURPOSE

Previous studies have reported that taller people have an increased risk of colorectal cancer (CRC). We examined the association of two height components-leg length and sitting height-with CRC risk in 14,532 individuals aged 45-64 years in the Atherosclerosis Risk in Communities study.

METHODS

Anthropometrics were measured at baseline (1987-1989). Incident CRC cases (n = 382) were ascertained from 1987 to 2012. Cox proportional hazards regression was used to estimate multivariable-adjusted hazard ratios for CRC and colon cancer across quintiles of sex-specific leg length and sitting height.

RESULTS

The highest (versus the lowest) quintile of leg length was associated with a 36% greater CRC risk (p-trend = 0.04), and 51% greater colon cancer risk (p-trend = 0.01). For the top four quintiles combined, risk was increased by 34% for CRC and by 45% for colon cancer versus the lowest quintile. Total height and sitting height were not significantly associated with CRC or colon cancer risk. A small number of cases (n = 57) limited our ability to conduct subgroup analyses for rectal cancer.

CONCLUSIONS

A positive association of leg length with CRC and colon cancer risk suggests that biological mechanisms leading to greater leg length during puberty may explain the association between taller height and CRC.

Adiponectin, Leptin, IGF-1, and Tumor Necrosis Factor Alpha As Potential Serum Biomarkers for Non-Invasive Diagnosis of Colorectal Adenoma in African Americans

The potential role of adiponectin, leptin, IGF-1, and tumor necrosis factor alpha (TNF-α) as biomarkers in colorectal adenoma is not clear. Therefore, we aimed to investigate the blood serum levels of these biomarkers in colorectal adenoma. The case-control study consisted of serum from 180 African American patients with colon adenoma (cases) and 198 healthy African Americans (controls) at Howard University Hospital. We used ELISA for adiponectin, leptin, IGF-1, and TNF-α detection and quantification. Statistical analysis was performed by t-test and multivariate logistic regression. The respective differences in median leptin, adiponectin, IGF-1, and TNF-α levels between control and case groups (13.9 vs. 16.4), (11.3 vs. 46.0), (4.5 vs. 12.9), and (71.4 vs. 130.8) were statistically significant (P < 0.05). In a multivariate model, the odds ratio for adiponectin, TNF-α, and IGF-1 were 2.0 (95% CI = 1.6-2.5; P < 0.001), 1.5 (95% CI = 1.5(1.1-2.0); P = 0.004), and 1.6 (95% CI = 1.3-2.0; P < 0.001), respectively. There was a positive correlation between serum adiponectin and IGF-1 concentrations with age (r = 0.17, P < 0.001 and r = 0.13, P = 0.009), TNF-α, IGF-1, and leptin concentration with body mass index (BMI) (r = 0.44, P < 0.001; r = 0.11, P = 0.03; and r = 0.48, P < 0.001), respectively. Also, there was a negative correlation between adiponectin and leptin concentrations with BMI (r = -0.40, P < 0.001), respectively. These data support the hypothesis that adiponectin, IGF-1, and TNF-α high levels correlate with higher risk of colon adenoma and can thus be used for colorectal adenomas risk assessment.

Genetic Basis for Colorectal Cancer Disparities

African Americans suffer the highest burden from colorectal cancer (CRC) in the USA. Studies have suggested that healthcare access and poorer utilization of preventive services may be playing more of a role in this disparity. However, African Americans also tend to develop CRC at younger ages and are more likely to have proximal cancers. This raises the possibility of higher genetic predisposition to CRC among African Americans and this has not been well studied. In this article, we reviewed possible genetic basis underpinning biological differences in CRC burden in the USA.

Circulating levels of IGF-1, IGFBP-3, and IGF-1/IGFBP-3 molar ratio and colorectal adenomas: A meta-analysis

BACKGROUNDS

Insulin-like growth factor-1(IGF-1) promotes cell proliferation and inhibits apoptosis, and is thereby implicated in carcinogenesis. Insulin-like growth factor binding protein-3 (IGFBP-3) may antagonize IGF-1 action, leading to inhibition of the potential tumorigenicity of IGF-1. We conducted this meta-analysis to estimate the association between IGF-1, IGFBP-3 and IGF-1/IGFBP-3 ratio and the risk of colorectal adenomas (CRAs). Further, we investigated whether this association was different between occurrent and recurrent CRA, by adjustment for obesity, and by advanced CRA.

MATERIALS AND METHODS

Pubmed and Embase were searched up to April, 2015 to identify relevant observational studies and summary odds ratio (OR) and the corresponding 95% confidence interval (95% CI) was estimated using a random-effects model.

RESULTS

A total of 12 studies (11 studies including 3038 cases for IGF-1, 12 studies including 3208 cases for IGFBP-3, and 7 studies including 1867 cases for IGF-1/IGFBP-3 ratio) were included in this meta-analysis. The summary ORs of occurrent CRA for the highest versus lowest category of IGF-1, IGFBP-3 and IGF-1/IGFBP-3 ratio were 1.13 (95% CI: 0.95-1.34), 0.99 (0.84-1.16), and 1.05 (0.86-1.29), respectively. Higher IGF-1 and IGF-1/IGFBP-3 ratio were significantly associated with decreased risk of recurrent CRA (OR for IGF-1=0.60 [95% CI: 0.42-0.85]; IGF-1/IGFBP-3 ratio=0.65 [0.44-0.96]). A stratified analysis by advancement of occurrent CRA produced a significant summary OR of IGF-1 for advanced CRA (OR=2.21 [1.08-4.52]) but not for non-advanced CRA (OR=0.89 [0.55-1.45]). We did not find significant publication bias or heterogeneity.

CONCLUSION

Circulating levels of IGF-1, IGFBP-3 and their molar ratio were not associated with the risk of occurrence of CRA, but IGF-1 was associated with the increased risk for occurrence of advanced CRA.

Reduced utility of serum IGF-1 levels in predicting retinopathy of prematurity reflects maternal ethnicity

AIMS

To validate known risk factors and identify a threshold level for serum insulin-like growth factor 1 (IGF-1) in the development of severe retinopathy of prematurity (ROP) in an ethnically diverse population at a tertiary neonatal unit, 2011-2013.

METHODS

A prospective cohort masked study was conducted. Serum IGF-1 levels at 31, 32 and 33 weeks were measured and risk factor data collected including gestational age (GA), birth weight (BW), absolute weight gain (AWG) and maternal ethnicity. The eventual ROP outcome was divided into two groups: minimal ROP (Stages 0 and 1) and severe ROP (Stage 2 or worse including Type 1 ROP).

RESULTS

36 patients were recruited: 14 had minimal ROP and 22 severe ROP. Significant differences between the groups were found in GA, BW, AWG and IGF-1 at 32 and 33 weeks. There was minimal rise in IGF-1 in Stage 2 patients and/or black patients (p=0.0013) between 32 and 33 weeks but no pragmatic threshold level of IGF-1 that could distinguish between minimal or severe ROP.

CONCLUSIONS

There were significant differences in GA, BW, AWG and IGF-1 at 32 and 33 weeks between those babies with severe ROP and those with minimal ROP. However, there was no threshold level of IGF-1 at a time point between 31 and 33 weeks that can be used to exclude a large proportion of babies from screening. We also found ethnic differences in IGF-1 levels with infants born to black mothers having significantly lower IGF-1 levels at 32 and 33 weeks gestation. The determination of ROP risk using IGF-1 is a race-specific phenomenon.