The Oxidative Balance Score And Risk Of Colorectal Cancer Development In European Populations

So Yeon KONG, International Agency for Research on Cancer (IARC-WHO), France

1 Section of Nutrition and Metabolism, International Agency for Research on Cancer (IARC-WHO), Lyon, France.
2 Department for Determinants of Chronic Diseases (DCD), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
3 Department of Epidemiology and Biostatistics, The School of Public Health, Imperial College London, London, United Kingdom.
4 Department of Social & Preventive Medicine, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.

Purpose: Oxidative stress and antioxidant status have been implicated in the etiology of several major chronic diseases, including various cancers such as colorectal cancer (CRC). Recently, a comprehensive score called the Oxidative Balance Score (OBS) has been developed combining dietary and/or biomarker measures of oxidative damage and antioxidant defence. Our objective was to assess the association of the OBS with CRC development using data from a large prospective cohort study.

Methods: OBS, comprised of 13 a priori selected pro- and anti-oxidant exposures (Dietary Factors: polyunsaturated fatty acids; Biomarkers: vitamin C, lycopene, α-/ β-carotene, lutein, β-crypoxanthin, zeaxanthin, retinol, α-tocopherol; Lifestyle Factors: alcohol consumption, smoking status, and body weight/waist circumference) was calculated using data from a CRC case-control study nested within the EPIC cohort. Conditional logistic regression was used to estimate multivariable-adjusted odds ratios (OR) and 95% confidence intervals (95%CI) for risk of CRC (and its anatomical sub-site) in relation to OBS. Effect modification by various factors relevant to CRC was also assessed. A total of 1,264 complete case-control pairs of first incident CRC cases (colon n=805; rectal n=459) and their matched controls were included in the analysis.

Results: Higher OBS, which represents predominance of anti-oxidants over pro-oxidants, was not associated with CRC risk (OR=0.90; 95%CI, 0.63-1.29, highest vs. lowest quartile). Analyses by CRC sub-sites showed a statistically significant association for colon (OR=0.58; 95%CI, 0.35-0.93), but not rectal cancer (OR=1.38; 95%CI, 0.78-2.43). 

Conclusions: In this large prospective cohort of European populations, OBS did not show an association with risk of CRC development overall, but findings by anatomical sub-site suggest an inverse association for colon but not rectal cancer.