Understanding current guidelines for colorectal cancer screening: A case-based approach

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ABSTRACTAfter a polyp or polyps are discovered on colonoscopy, many patients are being told to come back for repeat colonoscopy unnecessarily soon, thus diverting a scarce resource away from patients who may derive the most benefit—those with high-risk polyps and those who have never been screened.


  • All polyps do not pose the same risk. Small, left-sided hyperplastic polyps are nonneoplastic and require no increased follow-up. Adenomas are precancerous, and follow-up is determined by size, number, and histologic features.
  • The American College of Gastroenterology recommends that African Americans undergo screening under an average-risk strategy starting at age 45, as they have the highest incidence of colorectal cancer of any racial or ethnic group and present with it at a younger age.
  • People with a family history of colorectal polyps or cancer are recommended to start screening earlier—at age 40 or 10 years younger than the age of the relative that was affected (whichever is younger)—-and some of them should have colonoscopy more often than every 10 years
  • When deciding on the proper surveillance interval, one must take into account several details regarding the patient’s colonoscopy. Patients who have had an inadequate preparation, incomplete examination, or large lesions removed piecemeal should be recalled sooner.



Fewer than half of all people in the United States who should be screened for colorectal cancer have actually been screened. But at the same time, many people who have no or low-risk polyps on colonoscopy may be returning unnecessarily soon. Utilizing current screening and surveillance guidelines to direct patient care can reduce the number of unnecessary colonoscopies and improve surveillance of patients who may be at greater-than-average risk of colorectal cancer.

In this paper, we use several case examples to clarify the current guidelines on who should be screened, why, how, and how often.


Approximately 6% of American men and women develop an invasive colorectal neoplasm in their lifetime. Colorectal cancer is the second-leading cause of cancer death in the United States. In 2007, an estimated 153,760 people were newly diagnosed with colorectal cancer, and 52,180 people died of it.1

Yet, colorectal cancer is one of the few preventable cancers. Screening has been advocated as a way of preventing deaths by removing precancerous adenomas and detecting colorectal cancer early.2 Medicare has paid for screening colonoscopy since 1998, and since that time demand for this procedure has increased 112%.3,4 (See “Colonoscopy is the preferred test”.2,4–17)


National society guidelines recommend that people at average risk of colorectal cancer be screened starting at age 50 (Table 1).5,18–21 People are considered to be at average risk if they have no symptoms, do not have ulcerative colitis or Crohn’s colitis, and do not have a personal or family history of colorectal neoplasia.

The US Multi-Society Task Force on Colorectal Cancer19 suggests that people at average risk undergo one of the following:

  • Colonoscopy every 10 years
  • Flexible sigmoidoscopy every 5 years
  • Fecal occult blood testing every year
  • An air-contrast barium enema or computed tomographic (CT) colonography every 5 years
  • Fecal DNA testing, interval uncertain.

Anyone who has a positive result with any test other than colonoscopy should subsequently undergo colonoscopy.

Start screening sooner in people at higher risk

African Americans should undergo screening for colorectal cancer under an average-risk strategy starting at age 45, according to a position paper from the American College of Gastroenterology.4 Reasons for starting sooner are that African Americans have the highest incidence of colorectal cancer of any racial or ethnic group, and that they present with it at a younger age. In the years 1970–1994, 10.7% of cases of colorectal cancer in African Americans were detected before age 50 compared with 5.5% of cases in white people.22 In addition, compared with other ethnic groups, African Americans have a more proximal distribution of colorectal neoplasms, present with later-stage disease, and have lower survival rates.4

People with a family history of colorectal polyps or cancer should also start screening earlier—as early as age 40, or 10 years younger than the age at which the relative was affected—and some should be tested more often than every 10 years (see below).

Patients with ulcerative colitis or Crohn’s colitis. Current multisociety guidelines for colorectal cancer screening and surveillance in patients with ulcerative colitis or Crohn’s colitis are based on expert consensus and recommend a systematic biopsy protocol in some patients. When to begin surveillance in these patients and the specifics of the biopsy protocol are beyond the scope of this paper but are discussed in detail elsewhere.19


Case 1: A woman with a family history of cancer

A 55-year-old woman comes in for a routine physical examination. Her medical history is not remarkable, but her family history is: her maternal grandmother was diagnosed with colon cancer at age 75, her sister was diagnosed with endometrial cancer at age 34, and her mother was diagnosed with colon cancer at age 60. The patient underwent colonoscopy 5 years ago, and a 1.2-cm villous adenoma was removed from her right colon. She had been advised to have her next colonoscopy in 3 years.

Current recommendations for screening and surveillance differ based upon the number, age, and relationship of relatives affected with colorectal neoplasia (Table 1). The patient described above began screening at age 50 in accordance with the guidelines for people at average risk, but her extended family history was not taken into account.

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