Flexible sigmoidoscopy performed every five years and the annual stool blood test are the two most cost-effective strategies for screening colon cancer in asymptomatic adults aged 50-85 years, according to a new study funded by the Agency for Healthcare Research and Quality (AHRQ). The study is published in the Summer 2000 issue of the quarterly International Journal of Technology Assessment in Heath Care.
Rezaul K. Khandker, Ph.D. and colleagues compared the cost-effectiveness of eight screening strategies based on guidelines published in 1997 by the American Gastroenterological Association. The cost-effectiveness analysis measured the costs arising from screening against the gains that it yielded compared to doing no screening. Flexible sigmoidoscopy, a screening technique to examine the lining of the last part of the colon, conducted every five years ranked lowest in terms of cost per life-year saved at $12,636 in 1994 dollars, followed by the annual stool test, a technique to detect blood leaking from a polyp or tumor in the colon, at $14,394.
Colonoscopy, a costly procedure that directly examines the entire colon and permits immediate removal of precancerous polyps, is inherently the most effective strategy. The study found that reducing the cost of colonoscopy by 50 percent would make performing this test the second most-cost-effective choice if performed every 10 years. The study showed that the appeal of alternative screening strategies was dependent on how many years it took for a polyp in the colon to undergo the genetic changes that
transform the growth into cancer.
After sigmoidoscopy every five years and the annual stool blood testing, the other strategies, in the order of declining cost-effectiveness under the likeliest assumptions, were sigmoidoscopy every three years, double-contrast barium enema every five years, colonoscopy every ten years, annual stool blood testing plus sigmoidoscopy every five years, annual stool blood testing plus sigmoidoscopy every
three years, and colonoscopy every five years.
These cost-effectiveness ratios compared favorably with other screenings or prevention alternatives. For example, mammography screening for women between the ages of 50 and 69 had a cost-effectiveness ratio of $21,400 in 1995 dollars. The Pap smear, with AutoPap, an assisted rescreening technology, conducted every two and three years for women aged 20 to 65 years yielded $42,666 and $16,259, respectively, using 1996 dollars.
The full report from this study, Cost-Effectiveness Analysis of Colorectal Cancer Screening and Surveillance Guidelines (AHRQ Publication No. 01-0003), is in press and will be available from the AHRQ Publications Clearinghouse (1-800-358-9295) in late fall 2000.