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  • – Adults.


AAFP 2018, NCCN 2020

  • Modifiable Risk Factors

    • Diet:

      • Advise patients to increase consumption of fruits, non-starchy vegetables, and whole grains. Preferentially optimize nutrition from natural food sources rather than dietary supplements.

      • Cholesterol: 2-fold increased risk of CRC with increased intake.

      • Fat: 25% increased risk of serrated polyps with increased fat intake.

      • Dairy: 15% reduced risk of CRC with >8 oz of cow’s milk daily.

      • Fiber: No reduced risk of CRC or adenomatous polyps with increased fiber intake.

      • Red and processed meat: 22% increased risk of CRC with increased red and processed meat intake.

    • Lifestyle:

      • Alcohol: 8% increased risk of CRC and 24% increased risk of serrated polyps. Reducing alcohol intake does not clearly lower risk for CRC or polyps.

      • Cigarettes: 114% increased risk of high-risk adenomatous polyps and CRC in current smokers.

      • Obesity: Bariatric surgery associated with 27% reduced risk of CRC in obese individuals. Increased BMI is associated with increased mortality from CRC.

      • Occupational physical activity: 25% decreased risk of colon cancer and 12% decreased risk of rectal cancer.

      • Recreational physical activity: 20% decreased risk of colon cancer and 13% decreased risk of rectal cancer.

    • Medications:

      • Statins: Weak evidence that statin use ≥5 y is associated with decreased risk of advanced adenomatous polyps.

      • Calcium: 26% reduced risk of adenomatous polyps; 22% reduced risk of CRC in individuals taking 1400 mg daily calcium compared to 600 mg.

  • Polyp Removal

      • Based on fair evidence, removal of adenomatous polyps reduces the risk of CRC, especially polyps >1 cm. (Ann Intern Med. 2011;154:22) (Gastrointest Endosc. 2014;80:471)

      • Based on fair evidence, complications of polyp removal include perforation of the colon and bleeding estimated at 7–9 events per 1000 procedures.

  • Interventions Without Benefit

      • Vitamin D.

      • Folic acid.

      • Antioxidants.


  • – Aspirin: Associated with 40% decreased CRC incidence after 5–10 y of use.

    • Initiate low-dose aspirin for primary prevention of cardiovascular disease and CRC in persons aged 50–59 y with a 10-y cardiovascular event risk of ≥10%, no increased risk for bleeding, life expectancy of ≥10 y, and who are willing to take low-dose aspirin daily for 10 y. (USPSTF. Aspirin Use to Prevent Cardiovascular Disease and Colorectal Cancer. 2016.)

    • Individualize decision to initiate low-dose aspirin for persons 60–69 y of age with similar risk profile, as there is increased risk for bleeding and decreased CRC prevention benefit.

    • Insufficient evidence to initiate aspirin in persons <50 or ≥70 y of age.


  • Am Fam Physician. 2018;97(10):658-665.

  • – NCCN. Colorectal Cancer Screening. 2020:1-61.

  • – USPSTF. Aspirin Use to Prevent Cardiovascular Disease and Colorectal Cancer. 2016.


  • – Average-risk adults who have undergone baseline screening colonoscopy.

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