Insulin resistance, central obesity, and risk of colorectal adenomas.
BACKGROUND
Increasing evidence supports insulin resistance (IR) as the underpinning of the obesity-colorectal neoplasia link. The homeostasis model assessment-IR (HOMA-IR) is a widely accepted index of evolving hyperinsulinemia and early IR. Studies of the relation between HOMA-IR and colorectal adenomas are limited. Therefore, the authors sought to determine the associations of HOMA-IR and central obesity (waist to hip ratio [WHR]) with risk of colorectal adenomas in a screening colonoscopy-based study.


METHODS
The authors collected lifestyle information and fasting blood samples from 1222 participants (320 incident adenoma cases and 902 without adenomas) before their screening colonoscopies. Unconditional logistic regression models were used to assess risk associations.


RESULTS
In multivariate analysis of participants (n = 1093) reporting no antidiabetic medication use, those in the top quartile of WHR were twice as likely (odds ratio [OR], 2.18; 95% confidence interval [CI], 1.33-3.57; P-trend = .003) and those in the top quartile of HOMA-IR were 63% more likely (OR, 1.63; 95% CI, 1.09-2.44; P-trend = .01) to have adenomas compared with those in the bottom quartiles. Stratified analysis revealed a statistically significant interaction between HOMA-IR and sex (P-interaction = .04), with the association largely limited to men; compared with those in the bottom tertile, men in the top tertile of HOMA-IR were twice more likely to have adenomas (OR, 2.11; 95% CI, 1.18-3.78; P-trend = .01).


CONCLUSIONS
The results support central obesity and insulin resistance, particularly in men, as important risk factors for the development of early colorectal neoplasia.
Cancer Control and Population Sciences Program, University of Puerto Rico Comprehensive Cancer Center, San Juan, Puerto Rico.
Ana Patricia
AP
Ortiz
Cheryl L
CL
Thompson
Amitabh
A
Chak
Nathan A
NA
Berger
Li
L
Li
D000236:Adenoma / Q000209:etiology*; D001786:Blood Glucose; D015179:Colorectal Neoplasms / Q000209:etiology*; D005260:Female; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D056128:Obesity, Abdominal / Q000150:complications*; D012307:Risk Factors; D049629:Waist-Hip Ratio
D001786:Blood Glucose