Components of the metabolic syndrome and colorectal cancer risk; a prospective study

To examine the relation of well-known factors of the metabolic syndrome (MetS) as well as related circulating factors, with risk of colorectal cancer.

We performed a case control study of 306 colorectal cancer cases and 595 matched controls nested in the Northern Sweden Health and Disease Cohort. Levels of C-peptide, glycated haemoglobin (HbA1c), leptin and adiponectin were measured in cryopreserved samples. Body mass index (BMI), systolic and diastolic blood pressure and fasting and post-load plasma glucose, had been measured in a subcohort. Conditional logistic regression was used to calculate odds ratios (OR) of disease, including risk assessments for the MetS factors: obesity (BMI>30 kg m(-2)), hypertension (blood pressure > or =140/90 mmHg or use of anti-hypertensive drugs) and hyperglycaemia (fasting glucose > or =6.1 mmol l(-1) or post-load glucose in capillary plasma > or =8.9 mmol l(-1)).

None of the studied variables were significantly associated with risk across quartiles. Presence of obesity, hypertension and hyperglycaemia significantly increased the risk of colorectal cancer; OR for three vs null factors was 2.57 (95% Confidence Interval [CI] 1.20-5.52; P (trend)=0.0021), as compared to a 30 to 70% increased risk for the factors in single. Similarly, top decile levels of C-peptide, HbA1c and leptin/adiponectin ratio were associated with an increased risk; ORs for top vs deciles 1-9 were 1.56 (95% CI 0.93-2.62; P=0.090), 1.83 (95% CI 1.00-3.36; P=0.051) and 1.50 (95% CI 0.83-2.71; P=0.18), respectively.

Our study support the view that components of the MetS increase risk of colorectal cancer, and further suggests that only very high levels of metabolic factors confer an increased risk.