What are the risk factors for colorectal cancer (CRC)?

Updated: Jun 06, 2020
  • Author: Jaime Shalkow, MD, FACS; Chief Editor: Cameron K Tebbi, MD  more...
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In adults, CRC is largely preventable by the adoption of a healthy lifestyle, including diet and physical activity. Obesity is a well-documented risk factor for many types of malignancies, including CRC. [45]

Diet affects the risk of developing CRC. Both red and processed meats could increase the risk, whereas fiber, fruit, and vegetables may decrease it. [46]  Other dietary factors, such as fish, vitamins, minerals, and coffee, might have potential effects on the risk of developing CRC. However, factors responsible for adult CRC are unlikely to exert a major effect on children, in whom the majority of CRC cases occur spontaneously. [18]

CRC in adolescents and young adults may be associated with a familial cancer syndrome. However, whereas inherited cancer syndromes are more likely to affect a younger population, most CRC cases in adolescents and young adults are sporadic. Only 22% of adolescents and young adults with CRC have a family history of the disease. [3]

Several inherited polyposis syndromes predispose to CRC, including familial adenomatous polyposis (FAP), MutYH-associated polyposis, juvenile polyposis syndrome, Cowden syndrome, and Peutz-Jeghers syndrome. Colonoscopy with polypectomy of adenomatous polyps results in a 76-90% reduction in the incidence of colon cancer in appropriately screened individuals. Thus, for patients with inherited polyposis syndromes, colonoscopic surveillance is recommended between 10 and 15 years of age.

Proper polypectomy technique decreases the risk of residual polyps and, thus, reduces interval CRC rates. Advanced polypectomy techniques, such as endoscopic mucosal and submucosal resections, have a role in the nonsurgical management of large polyps. [47]

The timing of surgery depends on the burden of polyps, presence of dysplasia, genotype, and emotional maturity. It is often delayed until after age 18 years.

Several new syndromes have been defined that give rise to CRC. A rare form of hypermutated microsatellite-stable tumor results from mutation in the POLE gene, which plays a critical role in proofreading to identify and remove mispaired nucleotides during DNA replication. [48]

Other risk factors include prior abdominal radiation for the treatment of childhood malignancies, and inflammatory bowel disease, especially ulcerative colitis. The risk of CRC in ulcerative colitis increases with the extent of the disease and duration of inflammation. CRC risk is estimated at 2%, 8%, and 18% in the first, second, and third decades of active ulcerative colitis, respectively. [49]

By virtue of age alone, all adolescents and young adults with a new diagnosis of CRC should be referred for genetic counseling and testing.

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