A Western dietary pattern is associated with risk of colorectal cancer subtypes

Abstract

Background: The incidence rate of colorectal cancer (CRC) in Australia is one of the highest in the world. A poor diet may be associated with risk of CRC. Aim: To identify dietary patterns in an Australian population and determine their associations with the risk of CRC subtypes (proximal colon cancer, distal colon cancer and rectal cancer). Methods: We used dietary intake data from adults aged 40-70 years old from the 2005-2007 Western Australian Bowel and Health Study (n= 1904; 899 cases and 1005 controls), a case-control study of CRC. Using data from a food frequency questionnaire, dietary patterns were identified using principal component analysis. We used binary and multinominal logistic regression models to test associations between the identified dietary patterns and risk of CRC subtypes adjusting for age, sex, socioeconomic status, physical activity, smoking and body mass index at 40 years of age. Results: We identified two major dietary patterns: healthy (high in vegetables, legumes and fruit; low in takeaway foods) and Western (high in meat, fried fish, fried potatoes and beer; low in wholegrains and dairy). The Western dietary pattern was associated with an increased risk of proximal colon cancer (odds ratio for highest versus lowest quartile = 1.28, 95% confidence interval = 0.83-1.97) and distal colon cancer (odds ratio for highest versus lowest quartile = 1.58, 95% confidence interval = 1.01-2.47). There were no statically significant associations between the healthy dietary pattern and risk of CRC. Conclusions: This study further confirms that dietary patterns characterised by high intake of meat and fried foods, and low in wholegrains, are associated with an increased risk of colon cancer. 'So what'/Implications: Dietary advice aiming to reduce the risk of CRC in the Australian population should emphasis the increased risk of colon cancer associated with consuming a Western-type diet.