Sessile serrated lesions (SSL) are recognised precursors to colorectal cancer. Little is known about risk factors for SSL due to their relatively recent clinical recognition as a cancer precursor and routine documentation of cases. Lifestyle and diet-related information were collected using validated questionnaires in a colonoscopy-based case–control study in Australia (257 SSL cases, 239 conventional adenoma (CA) cases, 180 polyp-free controls). A posteriori dietary patterns were derived from self-reported dietary intake in the past 12 months using principal component analysis. Multivariable-adjusted OR and 95 % CI were used to examine associations between lifestyle factors and dietary patterns on risk of SSL and CA v. polyp-free controls and SSL v. CA using logistic regression modelling. Use of anti-inflammatory medications was associated with reduced SSL risk (OR = 0·61; 95 % CI 0·38, 1·00), while current smoking was associated with increased SSL risk (OR = 1·96; 95 % CI 1·09, 3·53). Unlike CA, SSL risk was not increased by hormone replacement therapy use and current alcohol consumption but was increased by taller height. Higher adherence to a dietary pattern featuring processed meats, ready-made convenience foods and high-energy drinks was associated with increased SSL risk (OR = 2·13; 95 % CI 1·13, 4·00; Ptrend = 0·03) and CA (OR = 2·60; 95 % CI 1·32, 5·09; Ptrend = 0·005). Compared with CA, a dietary pattern featuring wholegrains, low-fat dairy products, nuts, seeds and oily fish was associated with reduced SSL risk (OR = 0·60; 95 % CI 0·36, 0·98; Ptrend = 0·04). This study supports a healthy diet as primary prevention for both SSL and CA and reinforces smoking as a risk factor for SSL.

Bowel cancer risk is strongly influenced by lifestyle factors including diet and physical activity. Several studies have investigated the effects of adherence to the World Cancer Research Fund (WCRF)/American Institute for Cancer Research (AICR) cancer prevention recommendations on outcomes such as all-cause and cancer-specific mortality, but the relationships with molecular mechanisms that underlie the effects on bowel cancer risk are unknown. This study aimed to investigate the relationships between adherence to the WCRF/AICR cancer prevention recommendations and wingless/integrated (WNT)-pathway-related markers of bowel cancer risk, including the expression of WNT pathway genes and regulatory microRNA (miRNA), secreted frizzled-related protein 1 (SFRP1) methylation and colonic crypt proliferative state in colorectal mucosal biopsies. Dietary and lifestyle data from seventy-five healthy participants recruited as part of the DISC Study were used. A scoring system was devised including seven of the cancer prevention recommendations and smoking status. The effects of total adherence score and scores for individual recommendations on the measured outcomes were assessed using Spearman’s rank correlation analysis and unpaired t tests, respectively. Total adherence score correlated negatively with expression of Myc proto-oncogene (c-MYC) (P=0·039) and WNT11 (P=0·025), and high adherers had significantly reduced expression of cyclin D1 (CCND1) (P=0·042), WNT11 (P=0·012) and c-MYC (P=0·048). Expression of axis inhibition protein 2 (AXIN2), glycogen synthase kinase (GSK3β), catenin β1 (CTNNB1) and WNT11 and of the oncogenic miRNA miR-17 and colonic crypt kinetics correlated significantly with scores for individual recommendations, including body fatness, red meat intake, plant food intake and smoking status. The findings from this study provide evidence for positive effects of adherence to the WCRF/AICR cancer prevention recommendations on WNT-pathway-related markers of bowel cancer risk.

Whole-grain foods such as oats may protect against colorectal cancer and have benefits on inflammatory bowel disease and coeliac disease. The present study aimed to systematically review the literature describing intervention studies that investigated the effects of oats or oat bran on risk factors for bowel disease. A literature search was conducted using Embase, Medline and the Cochrane library, which identified 654 potential articles. Thirty-eight articles describing twenty-nine studies met the inclusion criteria. Two studies carried out in participants with a history of colorectal adenomas found no effects of increased oat-bran intake on indirect risk makers for colorectal cancer. One of two interventions with oat bran in patients with ulcerative colitis showed small improvements in the patients' conditions. Most of the eleven studies carried out in adults with coeliac disease showed no negative effects of uncontaminated oat consumption. The fourteen studies carried out in volunteers with no history of bowel disease suggest that oats or oat bran can significantly increase stool weight and decrease constipation, but there is a lack of evidence to support a specific effect of oats on bowel function compared with other cereals. A long-term dietary intake of oats or oat bran could benefit inflammatory bowel disorders, but this remains to be proven. A protective effect on colorectal adenoma and cancer incidence has not yet been convincingly shown. The majority of patients with coeliac disease could consume up to 100 g/d of uncontaminated oats, which would increase the acceptability of, and adherence to, a gluten-free diet.