What is a recognized risk factor for colorectal cancer?

Risk Factors for Colorectal Cancer

Chronic ulcerative colitis and Crohn's disease are recognized risk factors for colorectal cancer, not irritable bowel syndrome, low-protein diet, low vitamin intake, Turner syndrome, or low-fat diet.

Established Risk Factors for Colorectal Cancer

Inflammatory Bowel Disease

• Chronic ulcerative colitis and Crohn's disease significantly increase the risk of developing colorectal cancer 1
• Inflammatory bowel disease is associated with a nearly 3-fold increased risk of colorectal cancer (RR = 2.93) 2
• The risk exists for ulcerative colitis by decade of disease and is higher in pancolitis 1
• Inflammation is a recognized risk factor for progression to colorectal neoplasia 1

Family History and Hereditary Syndromes

• Family history of colorectal cancer in a first-degree relative doubles the risk of developing colorectal cancer 1
• Hereditary syndromes significantly increase risk, including:
  • Familial adenomatous polyposis (FAP) 1
  • Hereditary non-polyposis colorectal cancer (HNPCC) 1
  • Attenuated familial adenomatous polyposis syndromes 1

Personal Medical History

• Past history of colorectal cancer or adenomas 1
• Presence of colonic strictures in ulcerative colitis 1
• Multiple postinflammatory pseudopolyps 1
• Primary sclerosing cholangitis (PSC) increases risk 4-fold compared to patients with UC but without PSC 1

Lifestyle Factors

• Physical inactivity 1, 3, 2
• Obesity 1, 3, 2
• High consumption of red or processed meat 1, 4, 2
• Alcohol consumption 1, 4
• Cigarette smoking 3, 2

Non-Risk Factors (Not Associated with Increased Risk)

Irritable Bowel Syndrome (IBS)

• IBS is not a recognized risk factor for colorectal cancer 5
• A Danish nationwide cohort study actually found a decreased risk of colorectal cancer in the period 1-10 years after an IBS diagnosis 5
• The initial increased risk observed within the first 3 months after IBS diagnosis is likely due to diagnostic confusion because of overlapping symptomatology, not a true causal relationship 5

Dietary Factors Without Established Risk

• Low-protein diet is not established as a risk factor in major guidelines 1
• Low vitamin C and E intake are not specifically identified as risk factors in major guidelines 1
• Low-fat diet is not associated with increased colorectal cancer risk; in fact, high-fat consumption is associated with increased risk 3

Other Non-Risk Factors

• Turner syndrome is not identified as a risk factor for colorectal cancer in any of the guidelines 1

Clinical Implications

• Patients with inflammatory bowel disease (ulcerative colitis and Crohn's disease) should undergo more intensive surveillance for colorectal cancer 1
• The risk of colorectal cancer in inflammatory bowel disease increases with disease duration, with significant risk after 8 years of disease 1
• Patients with primary sclerosing cholangitis should commence annual colonoscopy from the time of diagnosis 1
• Lifestyle modifications including increased physical activity, maintaining healthy weight, limiting red meat consumption, and avoiding smoking can help reduce colorectal cancer risk 3, 4, 2