Screening of Colorectal Cancer

Fecal occult blood testing

The early evidence of the benefit of CRC screening with fecal occult blood testing (FOBT) demonstrated a shift in screen-detected cancers to an earlier stage with fewer Duke's D screen-detected cancers as compared with controls [5]. This stage shift was challenged quickly, however, as possibly caused by length bias and lead time bias. Length bias suggests that screening would pick up cancers that are slow growing more often than cancers that are more aggressive, and lead time bias suggests that

Adenomas

The most frequent outcome of screening is not cancer but an adenomatous polyp [6]. These polyps can be removed expeditiously by colonoscopy as an outpatient procedure, with the entire colon being examined in 15 to 20 minutes. This was a major advance compared with the exploratory laparotomy and multiple colotomies that were performed in the past. The feasibility of removing polyps through the colonoscope was reported in the mid-1970s. Shortly thereafter, the National Polyp Study was organized

Risk factors

Factors that increase the risk for development of CRC include a personal or family history of CRC or adenoma, a history of long-standing colitis caused by inflammatory bowel disease (eg, ulcerative colitis or Crohn's disease), and a genetic predisposition caused by a hereditary polyposis or nonpolyposis syndrome (Boxes 1 and 2).

History of colorectal adenoma

Most CRCs develop from a benign, premalignant precursor lesion through what is commonly referred to as the “adenoma to carcinoma sequence.” This pathway describes a

Average-risk screening

The initial approach to CRC screening relies on a thorough risk assessment of a patient. Asymptomatic individuals are candidates for routine screening, whereas individuals at increased risk because of a personal or family history of CRC or adenoma, inflammatory bowel disease, or a hereditary colon cancer syndrome are at high risk and require individualized risk specific recommendations for screening and surveillance.

All average-risk men and women should begin CRC screening at age 50. Several

Family history of colorectal cancer and adenomas

Individuals who have one or two first-degree relatives who are affected with CRC or adenomas at an average age of less than 60 are at increased risk. These patients should undergo screening of the entire colon beginning at age 40 or, if younger, 10 years younger than the earliest diagnosed cancer or adenoma. For patients with more than two first-degree relatives who are affected with colon cancer and no history of a polyposis syndrome, one should consider a diagnosis of HNPCC and recommend

History of colorectal adenoma

Colonoscopy is the preferred surveillance examination in patients who have had a colorectal adenoma removed in the past. The recurrence rate of adenomas in patients after initial polypectomy is high enough to justify periodic follow-up. Ideally, all synchronous adenomas are removed at the time of the initial polypectomy. The frequency of missed synchronous lesions, primarily small and tubular, has been reported to be 15% to 25%, however [43], [44]. A surveillance program should provide an

Screening rates

Screening rates for CRC are low and well below those for mammography. National health interview surveys have demonstrated this fact consistently. In the United States, only 20% of people over age 50 have had fecal occult blood tests, and 33% have had an endoscopic screening test in the previous 5 years [21]. One of the most frequent reasons for not getting screened (88%) is that “it was not recommended by my doctor,” according to one survey [6]. Health care providers play an important role in