Colorectal Cancer Prevention

1. See Also
   1. Colorectal Cancer Screening
2. Risk Factors: Colorectal Cancer
   1. Age >50 years (accounts for 90% of Colon Cancer)
   2. Past Medical History
      1. Inflammatory Bowel Disease (Ulcerative Colitis)
      2. Adenomatous polyps >5mm (Confers RR of 2-3 times)
      3. Hamartomatous polyposis syndromes
      4. Cholecystectomy
      5. Pelvic irradiation
   3. Family History
      1. First degree relative with Colon Cancer (RR=2-3x)
      2. Familial adenomatous polyposis
      3. Hereditary non-polyposis Colon Cancer
   4. Lifestyle related risks
      1. Tobacco abuse
      2. Obesity
         1. Men: BMI 35-40 associated with Colorectal Cancer mortality relative risk 1.8
         2. Women: BMI 35-40 associated with Colorectal Cancer mortality relative risk 1.4
         3. Calle (2003) N Engl J Med 348(17): 1625-38
   5. Dietary Risk Factors
      1. High Dietary Fat
         1. Saturated and polyunsaturated fat increases adenomatous polyp development
         2. High fat diet is not associated with Colorectal Cancer development
            1. Howe (1997) Cancer Causes Control 8:215-28
      2. Red Meat
         1. Foods with possible higher risk: Salt-cured, pickled, smoked, barbeque
         2. Mixed results from studies
3. Prevention: Colorectal Cancer
   1. High Physical Activity
   2. High fruit and vegetable intake
   3. High Dietary Fiber intake
      1. Previously recommended for longterm prevention
         1. However no data to support fiber in prevention of adenomas or Colorectal Cancer
      2. Does not prevent shorterm recurrent adenomas
         1. Schatzkin (2000) N Engl J Med 342:1149-55
      3. Sources
         1. Whole grain cereals
         2. Legumes
         3. Fruits and vegetables
         4. Water insoluble (wheat bran) fiber may be best
   4. High folate or methionine intake
   5. High Dietary Calcium intake (1200 mg qd)
      1. Prevents adenoma recurrence
         1. Baron (1999) N Engl J Med 340:101-7
      2. Decreases risk of histologically advanced polyps
         1. Wallace (2004) J Natl Cancer Inst 96:921-5
   6. Medications: None are recommended
      1. General
         1. Aspirin, NSAIDs, COX-2 Inhibitors not recommended
         2. Despite effectiveness in prevention, risks are high
         3. (2007) Am Fam Physician 76:109-113
      2. Aspirin
         1. Reduces adenoma Incidence in high risk patients
         2. Greatest risk reduction at >14 tablets per week
         3. Chan (2004) Ann Intern Med 140:157-66
      3. NSAIDs
         1. Sulindac prevented neoplasia in familial polyposis
         2. Janne (2000) N Engl J Med 342:1960-8
      4. COX-2 Inhibitors
         1. Celecoxib prevented neoplasia in familial polyposis
         2. Steinbach (2000) N Engl J Med 342:1946-52
      5. Postmenopausal Hormone Replacement
         1. Studies demonstrate lower overall Colon Cancer risk
         2. However, those diagnosed with Colon Cancer were at a more advanced stage
         3. Chlebowski (2004) N Engl J Med 350:991-1004
      6. Antioxidants
         1. No benefit with Beta Carotene, Vitamin A, Vitamin C, Vitamin E, Selenium
         2. Increased adenomatous polyp risk with Vitamin E
         3. Bjelakovic (2006) Aliment Pharmacol Ther 24:281-91
      7. Statins
         1. Observational studies demonstrate a 30% reduction in Colon Cancers
         2. Randomized controlled studies needed before a recommendation can be made
         3. Poynter (2005) N Engl J Med 352: 2184-2192
4. References
   1. Giovannucci (1995) N Engl J Med 333:609-14
   2. Wilkins (2008) Am Fam Physician 78(12): 1385-92