Urinary markers of nucleic acid oxidation and cancer in type 2 diabetes

AIMS/HYPOTHESIS: We investigated whether urinary markers of nucleic acid oxidation are associated with an increased risk of cancer in type 2 diabetes patients. METHODS: Urine samples from 1381 newly diagnosed diabetes patients were assayed for the oxidatively modified guanine nucleosides 8-oxo-7,8-dihydro-2′-deoxyguanosine (8-oxodG) and 8-oxo-7,8-dihydroguanosine (8-oxoGuo). Cox proportional hazards regression was used to examine the relationship between the urinary markers and cancer incidence. RESULTS: The crude analyses showed an association between overall cancer and urinary excretion of the RNA oxidation marker 8-oxoGuo (unadjusted hazard ratio for cancer per natural log increase in 8-oxoGuo 1.35 [95% CI, 1.01–1.81]), however, in the adjusted analyses, no significant associations between 8-oxodG or 8-oxoGuo and overall cancer were found. For site-specific cancers 8-oxodG was associated with breast cancer in the crude analyses (unadjusted hazard ratio for breast cancer per natural log increase in 8-oxodG was 2.37 [95% CI, 1.07–5.26]), although the association was attenuated in the adjusted analyses (sex- and age-adjusted hazard ratio 2.15 [95% CI, 0.92–5.02] and multivariate adjusted hazard ratio1.98 [95% CI, 0.95–4.10]). CONCLUSIONS: Urinary excretion of the nucleic acid oxidation markers 8-oxodG and 8-oxoGuo at the time of diagnosis was not associated with cancer overall in type 2 diabetes patients. For site-specific cancers, risk elevations were seen for breast cancer (8-oxodG). These findings should be examined in future and larger studies.