Dietary patterns and the risk of colorectal cancer and adenoma: a case control study in Iran

AIM: The aim of this study is to examine the relationship between dietary patterns and the risk of Colorectal Cancer (CRC) and adenomas. BACKGROUND: Dietary patterns have been shown to be associated with risk of CRC, but there are a few data on this context and its relationship with risk of colorectal adenomas as the precursors of the CRC. METHODS: This hospital-based case-control study was conducted in three major general hospitals in Tehran province, Iran. Data was collected (October 2016 to May 2018) from 129 colorectal cancer and 130 colorectal adenoma patients that confirmed by pathology and colonoscopy findings and 240 controls with non-neoplastic conditions and not afflicted with diet related chronic diseases. Dietary data were evaluated by 147-items semi-quantitative food frequency questionnaire. Multivariate logistic regression was used to estimate the relationship between dietary patterns and risk of colorectal cancer and colorectal adenoma. RESULTS: Three dietary patterns (healthy, western and traditional) were derived. After adjusting for confounders, the Healthy dietary pattern was associated with a decreased risk of Colorectal Cancer (OR=0.22, 95% CI=0.14-0.37) and Colorectal Adenoma (OR=0.43, 95% CI=0.27-0.69). Higher intake of the Westernized pattern was positively associated with risk of Colorectal Cancer (OR=3.5, 95% CI=2.13-5.19) and Colorectal Adenoma (OR=2.47, 95% CI=1.49-4.08). There was no significant association between traditional pattern and the Colorectal Cancer (OR=99, 95% CI=0.61-1.59) and Colorectal Adenoma (OR=0.85, 95% CI=0.54-1.35) risk. CONCLUSION: Our study suggested that the “Healthy” dietary pattern reduces the risk of Colorectal Cancer and Colorectal Adenoma, while the “Western” dietary pattern increases the risk of both Colorectal Cancer and Colorectal Adenoma.