E Case #7B

Heather Kelly-Hedrick, MD

July 23 - 27, 2001

A 50 year old woman presents to establish care.

PMH: unremarkable.

ROS: negative.

FH: unremarkable.

What are the recommendations for colorectal cancer screening and surveillance in asymptomatic people at average risk?

Offer to all men and women without risk factors beginning at age 50.  Options include:

1. Fecal occult blood screening each year.  Testing of two samples from each of three consecutive stools for the presence of FOB followed by colonoscopy has been shown in three randomized controlled trials to reduce the risk of death from colorectal cancer.  Disadavantages are FOBT fails to detect many polyps and some cancers.

2. Screening sigmoidoscopy with a flexible sigmoidoscope every five years.  Two case-control studies report a 60-70% reduction in mortality in patients screened and from a cohort study and a case-control study removing adenomatous polyps reduces risk of colorectal cancer by 76-90%. Disadvantages are sigmoidoscopy alone detects only about half of all colorectal cancers and polyps.

3. Combined FOBT and flex sig.  Recommended by ACG when resources, expertise, or reimbursement for screening colonoscopy are not available.

4. Colonoscopy every 10 years (the preferred screening strategy by the American College of Gastroenterology).  Although no study evaluating whether screening colonoscopy alone reduces the incidence or mortality from colorectal cancer in people at average risk of the disease evidence from a and b can be applied.  Cross-sectional studies show has a prevalence of detecting adenomas twice that detected on average by flex sig.  40% of cancers arise proximal to the splenic flexure.  Diagnosis and treatment can be done in a single session.  Disadavantages are greater risk (1 per several thousand perforation and bleeding compared to 1/100,000 with flex sig), need for sedation, cost, and appropriately trained experts need to be available.  Note:  as of July 1, 2001, the Medicare screening benefit has been expanded to include screening colonoscopy for average risk individuals once every 10 years.

5. Double-contrast BE every 5 to 10 years.  Less desirable.  No studies evaluating whether screening with DCBE reduces the incidence or mortality from colorectal cancer in people at average risk.  It has been thought that DCBT can image entire colon and detect cancers and large polyps almost as well as colonoscopy however, recent trials call this into question.

One week later, guaiac cards show one of three positive for occult blood.  Colonoscopy done and a 1.5 cm adenomatous polyp is found in the right colon and removed.

She now is at increased risk for colorectal cancer, what future screening does she need?  What other groups of people need more aggressive screening or surveillance due to increased colorectal cancer risks?

1. People with a history of adenomatous polyps.  If large (> 1 cm) or multiple adenomatous polyps offer repeat colonoscopy three years after the initial exam.  If first follow up is normal or only a single, small, tubular adenoma is found, the next exam can be in five years.

2. People with single first-degree relative with colorectal cancer diagnosed at age > or = 60:  Begin screening at age 40.  Preferred screening is colonoscopy every 10 yrs.  If with first-degree relative with adenomas at age > or = 60 yr, screening recommendations should be individualized.

3. People with single first-degree relative with colorectal cancer diagnosed at age <60 or multiple first-degree relatives with colorectal cancer:  Begin screening at age 40 or 10 yr younger than age of diagnosis of the youngest affected relative, whichever is first.  Preferred screening: colonoscopy every 3-5 yrs.

4. People with a family history of familial adenomatous polyposis(FAP) and hereditary non-polyposis colorectal cancer (HNPCC) need more aggressive screening (see references).

5. People with a history of colorectal cancer.  Offer colonoscopy within one year after resection with curative intent if adequate preop colonoscopy not done, otherwise offer colonscopy after three years and then, if normal, every five years.

6. People with inflammatory bowel disease.  Use colonoscopy for surveillance every one to two years beginning after 8 years of disease with pancolitis or after 15 years in those with colitis involving only the left colon.  If dysplasia found, consider colectomy.

References

Rex DK, Johnson DA, Lieberman DA, et al.  Colorectal cancer prevention 2000: screening recommendations of the american college of gastroenterology.  Am J Gastro 2000;95:868-77.

Winawer  SW, Fletcher  RH, Mille L, et al.  AGA guidelines: colorectal cancer screening: clinical guidelines and rationale.  Gastroentereology 1997;112:594-600.