Background: Colorectal cancer is one of the most commonly occurring cancers in China. Dietary fibre hasbeen thought to decrease the risk of colorectal cancer in Western countries. However, studies investigatingthe association between dietary fibre (particularly soluble and insoluble fibres) and colorectal cancer havehitherto been lacking in China.
Objective: This case-control study examined the effect of dietary fibre intakeon the risk of colorectal cancer, stratified by tumour site. Materials and
Methods: The study included 265 cases(colon cancer, 105; rectal cancer, 144; colon and rectal cancer, 16) and 252 controls residing in Qingdao. A foodfrequency questionnaire that included 121 food items was used to collect dietary information. Odds ratio (OR)and 95% confidence intervals (CI) were calculated using unconditional logistic regression analysis.
Results:For food groups, controls in the study consumed more vegetables, soy food and total fibre than did colorectalcancer patients (p<0.05). The intakes of fruit, meat and sea-food did not differ significantly between cases andcontrols. However, we did not find any association between soy food intake and colon cancer. We observed inverseassociations between total fibre intake and colorectal, colon and rectal cancer (Q4 vs Q1: OR=0.44, 95%CI, 0.27-0.73; OR=0.40, 95%CI, 0.21-0.76; OR=0.52, 95%CI, 0.29-0.91). Vegetable fibre intake showed similar inverseassociations (Q4 vs Q1: OR=0.51, 95%CI, 0.31-0.85; OR=0.48, 95%CI, 0.25-0.91; OR=0.53, 95%CI, 0.29-0.97). Inaddition, inverse associations were observed between soluble fibre and insoluble fibre and both colorectal cancerand colon cancer. No relationship was found between colorectal cancer and fruit, soy or grain fibre intakewhenthe results were stratified by tumour site.
Conclusions: The present study suggests that vegetable fibre and totalfibre play very important roles in protecting against colorectal cancer. Soluble and insoluble fibres were inverselyassociated with only colorectal cancer and colon cancer.