Colorectal cancer: Prevention vs. detection
Colon polyps may be removed at the time of colonoscopy.
The U.S. Multi-Society Task Force on Colorectal Cancer, the American Cancer Society, and the American College of Radiology have each published colorectal cancer (CRC) screening guidelines before, but Screening and Surveillance for the Early Detection of Colorectal Cancer and Adenomatous Polyps, 2008: A Joint Guideline represents the first such document carrying the imprimatur of all three groups.
Besides adding two newcomers (stool DNA [sDNA] and CT colonography [CTC]) to the list of recommended tests, the participating organizations take for the first time the unambiguous position that preventing CRC, rather than detecting it early, should be the primary goal of screening.
Primary-care providers (PCPs) have an “essential and often underappreciated” role in screening, says Durado Brooks, MD, director of prostate and colorectal cancer in the cancer control department of the American Cancer Society and an author of the Guideline. “When studies have looked at people who haven't been screened for colorectal cancer, a reason often given is ‘my doctor never talked to me about it.' Many PCPs don't realize their patients are waiting for them to bring up the topic.”
While choosing among tests is the patient's prerogative, “there are quite a few tests, and patients may not appreciate the differences among them,” Dr. Brooks comments. The PCP is often in the best position to explain the options, and the Guideline is intended to inform this “shared decision making,” he says.
Where earlier guidelines presented a menu of options, these prioritize them. “It is clear that all CRC screening tests are not created equal,” Dr. Brooks cautions. They fall into two categories: those highly likely to find cancer (fecal tests) and those that effectively identify precancerous polyps (“structural exams”) as well (see Table 1). Finding and removing such lesions can prevent cancer, he says.
“We've stated emphatically that if resources are available and patients are willing to undergo these somewhat more invasive tests, those that find both polyps and cancer at a high rate are recommended,” he says.
The Guideline also gives new emphasis to questions of quality and factors that influence sensitivity.