Colorectal cancer (CRC) accounts for 9.7% of all cancer cases and for 8% of all cancer-related deaths. Established risk factors include personal or family history of CRC as well as lifestyle and dietary factors. We investigated the relationship between CRC and demographic, lifestyle, food and nutrient risk factors through a case–control study that included 2062 patients and 2776 controls from Scotland. Forward and backward stepwise regression was applied and the stability of the models was assessed in 1000 bootstrap samples. The variables that were automatically selected to be included by the forward or backward stepwise regression and whose selection was verified by bootstrap sampling in the current study were family history, dietary energy, ‘high-energy snack foods’, eggs, juice, sugar-sweetened beverages and white fish (associated with an increased CRC risk) and NSAIDs, coffee and magnesium (associated with a decreased CRC risk). Application of forward and backward stepwise regression in this CRC study identified some already established as well as some novel potential risk factors. Bootstrap findings suggest that examination of the stability of regression models by bootstrap sampling is useful in the interpretation of study findings. ‘High-energy snack foods’ and high-energy drinks (including sugar-sweetened beverages and fruit juices) as risk factors for CRC have not been reported previously and merit further investigation as such snacks and beverages are important contributors in European and North American diets.
aDepartment of Environmental and Occupational Medicine, Liberty Safe Work Research Centre, University of Aberdeen, Aberdeen
bCentre for Population Health Sciences, College of Medicine and Veterinary Medicine
cColon Cancer Genetics Group, Institute of Genetics and Molecular Medicine
dSchool of Informatics, College of Science and Engineering, University of Edinburgh
eSchool of Nursing, Midwifery & Social Care, Faculty of Health, Life and Social Sciences, Edinburgh Napier University
fSouth East Scotland Genetic Service, Western General Hospital, Edinburgh, UK
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Correspondence to Evropi Theodoratou, PhD, Centre for Population Health Sciences, College of Medicine and Veterinary Medicine, University of Edinburgh, Teviot Place, Edinburgh EH8 9AG, UK Tel: +44 131 650 4335; fax: +44 131 650 6909; e-mail: email@example.com
Received January 30, 2013
Accepted May 21, 2013