Am Fam Physician. 2002;66(10):1985-1990
Screening for and removal of colorectal cancer and precancerous adenomatous polyps can decrease the incidence of colon disease. Because the various screening techniques have not been compared directly and the ages to start and stop screening have not been studied, the U.S. Preventive Services Task Force (USPSTF) relied on cost-effectiveness analyses using simulation models to compare various screening techniques and parameters among patients who are at average risk for colorectal cancer. The group focused on whether screening is cost-effective, if there is a preferred method of screening, and if there is a particular age that is best to start and stop screening. Pignone and associates searched several databases in the United States and the United Kingdom for studies on colorectal neoplasms and screening along with costs and cost analysis.
Life-years gained by screening and the cost per person for each recommended strategy were calculated. Each of the studies that met inclusion criteria considered one or more screening methods and considered all the direct costs involved, excluding patient time costs.
Concerning cost-effectiveness, all studies demonstrated that screening reduced deaths from colorectal cancer in adults older than 50 years. Most screening strategies had average cost-effectiveness ratios of $10,000 to $25,000 per year of life saved. Even if alternative worst-case assumptions about tumor natural history and treatment results were used, cost-effectiveness ratios remained less than $100,000 per life-year saved.
Concerning choice of the optimal screening method, the results are less obvious. If $20,000 per life-year saved is the maximum one is willing to pay, the results are unclear, with different studies finding either annual fecal occult blood testing (FOBT), sigmoidoscopy every five years, or colonoscopy every 10 years to be the most cost-effective technique. If a higher cost is allowed per life-year saved, colonoscopy every 10 years or a combination of annual FOBT with sigmoidoscopy every five years becomes more beneficial.
Concerning an appropriate age range for screening, data provide some support for starting at 50 years of age for men and women. The ending date beyond which screening is no longer cost-effective is less clear.
The authors conclude that screening for colorectal cancer among average-risk patients older than 50 years is clearly superior to no screening. However, the most cost-effective method of screening and at what age to stop screening are less clear. Patient preference should play a role until further studies are completed.
| Level of evidence* | Clinical implications |
|---|---|
| A | FOBT performed every two years is effective in reducing colorectal cancer mortality but less so than annual testing. |
| A | FOBT reduces the incidence of colorectal cancer. |
| B | Barium enema sensitivity is lower than previously estimated. |
| B | Colonoscopy is more accurate than flexible sigmoidoscopy and |
| FOBT for detecting colorectal neoplasia, but the implications for screening policy are unclear. | |
| B | DNA stool test and virtual colonoscopy show early promise for |
| detection of colorectal neoplasia, but further research is required. | |
| A | Increased fiber intake does not prevent recurrent colorectal adenomas in middle-aged adults. |
| A | Calcium supplements reduce the risk of recurrent colorectal adenomas. |
| A | NSAIDs, including COX-2 inhibitors, reduce the risk of adenomas in patients with high-risk familial syndromes. |
In another report in the same journal, the recommendations of the USPSTF include strong support for colorectal screening among men and women 50 years or older using periodic FOBT and sigmoidoscopy with or without FOBT. Evidence in support of colonoscopy or barium enema for colorectal screening is inadequate to make a specific recommendation.
editor's note: In an evidence-based review, Pignone and Levin looked at colon cancer screening and prevention (see accompanying table). The conclusions about screening in their article parallel those of the USPSTF, with the role of colonoscopy as the best or even a cost-effective screening technique still unclear. The best screening technique has not yet been identified. The review of prevention noted no benefit for increased fiber in adults with previous colorectal adenomas but some benefit for calcium supplementation in this population. Several nonsteroidal anti-inflammatory drugs, notably sulindac and celecoxib, reduce the risk of adenomas in persons with familial polyposis during the period that the medication is taken.—r.s.