Tumor risk biomarkers and physical activity in type 2 diabetes, patients with colorectal cancer and individuals without diabetes

Abstract

Biomarkers such as 8-oxo-2'deoxy-guanosine (8-oxo-dG), prostaglandin E2 alpha (PGE2 alpha), prostaglandin metabolites (PGEM) and 8-isoprostane (8-iso) may quantitatively reflect individual tumor risk including colorectal cancer (CRC) and may be useful in clinical management and prevention programs. To further clarify their role in a clinical setting we compared urinary excretion levels with regard to physical activity and other clinical and metabolic parameters in patients with longstanding (>5 years) type 2 diabetes (T2D) (moderate risk) and in those with curatively treated CRC (high risk for recurrence). Patients and methods: In this one center case-control study 60 patients with T2D and 40 patients with CRC were compared with 40 healthy controls. Levels of physical activity were assessed in MET-hr/wk. Urinary excretion of 8-oxo-dG, PGE2 alpha, PGEM and 8-iso were determined by HPLC-ESI mass-spectrometry and ELISA, respectively. Results: Urinary 8-oxo-dG excretion was 33.7% higher in T2D compared to controls (P=0.01), in CRC excretion was 83.6% higher (p<0.0001). There was a positive correlation with BMI (p=0.04) in all study participants. There were no significant correlations with the levels of physical activity and other clinical and metabolic parameters (HbA1c, pre-, post-prandial glucose). Urinary excretion of PGE2alpha, PGEM and 8-iso were similar in all study participants. Conclusions: This study provides quantitative biomarker data which may be useful in management and prevention programs. One important clinical application would be the implementation of biomarker data into risk prediction models to improve accuracy. The lack of correlation with the levels of physical activity does not preclude their value in interventional settings.