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Feature Article

Screening for colorectal cancer

Lennart Choo, Ian D Norton

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Abstract

With access to one of the few population-based colorectal cancer screening programs in the world, Australian patients have the opportunity to have bowel cancer prevention incorporated into their health maintenance plans. Screening asymptomatic people can detect cancers at an earlier, and therefore more curable, stage, resulting in a reduction in mortality.

Key Points

  • Screening asymptomatic people who are at average risk of colorectal cancer (CRC) can detect cancers at an earlier, and therefore more curable, stage, theoretically resulting in a reduction in mortality.
  • Three risk categories have been identified to stratify patients into appropriate screening programs – high, increased and average risk.
  • Patients with features of an inherited CRC syndrome are at high risk of CRC and should be advised to pursue genetic counselling and, if appropriate thereafter, genetic testing for significant gene mutations.
  • Individuals may be at increased risk of CRC based on family or personal history of previous adenomatous polyps or CRC, or a personal history of inflammatory bowel disease.
  • Patients with one first-degree relative before the age of 55 years or two first-degree relatives at any age with CRC should be screened regularly starting at the age of 50 years or 10 years before the age at which the earliest case of CRC occurred in the family.
  • Stool examinations are noninvasive tests that include faecal occult blood tests (FOBTs) such as faecal immunohistochemical testing (FIT) and also faecal DNA tests.
  • Direct detection of adenomatous polyps and CRC is possible with use of a barium enema, CT colonography, flexible sigmoidoscopy or colonoscopy.
  • Colonoscopy is the common end-point for all screening studies, and is considered the gold standard for the diagnosis of both colon and rectal polyps and malignancy.

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