Physicians appear to be performing surveillance colonoscopies at frequencies higher than those recommended by evidence-based medical guidelines, according to the results of a recent national survey published in the August 17 Annals of Internal Medicine. Dr. Pauline Mysliwiec, of the University of California, Davis School of Medicine, and colleagues sought to learn whether physicians followed recommended guidelines for surveillance colonoscopies, and what factors most influence a physician's decisions. The study warns that as the demand for colonoscopies in the United States increases, overperformance could tax limited physician resources and cause unnecessary risk to patients.

The National Cancer Institute (NCI)-funded survey of gastroenterologists and general surgeons about their opinions and practices regarding the use of surveillance colonoscopy in various clinical scenarios sought to find out how often physicians would recommend a colonoscopy and/or other procedures following an initial discovery of a colorectal abnormality in a healthy and asymptomatic 50-year-old patient.

Current recommendation guidelines vary among several professional societies, but generally suggest that colorectal cancer surveillance be conducted every 3 to 5 years, depending on the patient's risk (size and number of adenomas found in initial screenings). However, survey results indicate that many physicians recommend surveillance procedures at frequencies higher than the guidelines recommend. For example, in the case of a single small adenoma, a majority of gastroenterologists and general surgeons recommended surveillance colonoscopy, either alone or in conjunction with another procedure, at a frequency of 1 to 3 years, instead of 3 to 5 years.

More than 80 percent of the physicians in the study cited clinical evidence in scientific and medical journals as influential in their decisions, and scientific evidence was perceived as significantly more influential than medical guidelines. "Forces in the doctor's own practice may play a role, as well," said study co-author Dr. Martin Brown. "[These include] concerns about liability, community influence, and financial incentives."

Overuse of colonoscopy could affect quality of care. When performed on low-risk patients, colonoscopy's risks could outweigh the benefits in terms of an individual's inconvenience and procedural complications, forfeiting the advantages that could have been gained through surveillance. Unnecessary surveillance colonoscopies also may overtax an already burdened health care system. Overutilization can lead to reduced access and longer waiting periods for those at higher risk for developing colorectal cancer.

In the annual Report to the Nation on the Status of Cancer (1975-2001), published in the July 1 Cancer, the authors state that "decreases in colorectal cancer incidence and mortality rates have been largely attributed to the detection and removal of precancerous polyps, the early detection of tumors, and improved treatment." However, research indicates that an estimated three-fourths of persons who have identified lesions through screening colonoscopy are at minimal risk for developing colorectal cancer, and 10 percent or more of patients screened are found to have benign non-neoplastic lesions.

Other colorectal cancer screening and surveillance modalities include fecal occult blood test, sigmoidoscopy, and double-contrast barium enema.