Colonoscopy recommended as primary screening method for colorectal cancer, researchers report

American Society for Gastrointestinal EndoscopyOct 27 2009

Researchers from Taiwan report in a new study that unsedated colonoscopy for primary colorectal cancer screening is well accepted in a majority of patients. Sedation is typically used for colonoscopy to make the patient feel comfortable during the procedure. In Taiwan, colonoscopy is performed less frequently than sigmoidoscopy for colorectal cancer screening due to concerns over cost and availability. While sigmoidoscopy is generally accepted as a well tolerated procedure without sedation, many physicians and patients assume colonoscopy requires sedation for patients to be comfortable. Researchers compared unsedated colonoscopy with sigmoidoscopy to analyze factors associated with acceptance of the procedures and need for sedation. The study appears in the October issue of GIE: Gastrointestinal Endoscopy, the monthly peer-reviewed scientific journal of the American Society for Gastrointestinal Endoscopy.

Colonoscopy is recommended as the primary screening method for colorectal cancer and is the final common pathway for all other recommended screening tests. It is considered the "gold standard" for colorectal cancer screening because of the ability to diagnose and remove polyps (growths) before they become cancer. Colonoscopy utilizes a colonoscope, a tube with a light and video camera on the end, which allows the physician to see the entire colon. If a polyp is found, it can be removed immediately. Flexible sigmoidoscopy consists of a sigmoidoscope, a slender, lighted tube about the thickness of a finger. This allows the physician to look only at the inside of the rectum and lower part of the colon for cancer or polyps. This exam only evaluates about one-third of the colon; the other two-thirds are not examined. If polyps are found, the patient must return for a full colonoscopy.

The advantages of unsedated colonoscopy include the elimination of the risks associated with sedation, especially in patients with comorbidities; a reduction in the recovery time after the procedure; a decrease in the need for cardiopulmonary monitoring; and a significant reduction in cost.

"In Taiwan and many Asian countries, sedation is not routinely available and affordable, limiting the use of colonoscopic screening. When choosing between unsedated colonoscopy and sigmoidoscopy for screening, most patients undergo sigmoidoscopy because the majority of doctors and patients consider unsedated colonoscopy to be poorly accepted," said study lead author Hsiu-Po Wang, MD, National Taiwan University Hospital. "We compared patients who underwent either unsedated colonoscopy or sigmoidoscopy for primary colorectal cancer screening and found no significant differences in pain scores, patient acceptance, or need for sedation."

The prospective study was conducted from September 2006 to March 2007 by four experienced endoscopists at the Health Management Center of National Taiwan University Hospital. Patients who had not undergone previous sigmoidoscopy or colonoscopy were considered eligible and were asked to undergo either a sigmoidoscopy or colonoscopy without sedation. The choice of sigmoidoscopy or colonoscopy was at the discretion of the patient. A total of 261 (of approximately 1,400 eligible) patients participated in the study; 176 selected colonoscopy and 85 selected sigmoidoscopy. If the patient expressed intolerance of the unsedated examination, the patient could elect to stop the examination or receive sedation. All procedural variables, including biopsy (tissue sample), polypectomy (polyp removal), and other therapeutic procedures; time spent in the scope insertion phase; and total procedure time were recorded. To assess disparities in endoscopists' skill, insertion time was stratified by procedure type and was compared among the endoscopists.

Pain was evaluated by an 11-point visual analog scale from 0 to 10 (0: no pain, 10: worst pain). Acceptance of the procedure was graded in four categories: excellent, good, fair, and poor. A trained nurse, who was blinded to the type of procedure, evaluated the severity of pain, acceptance of the procedure, and need for sedation immediately after the examination in a separate room without the presence of the endoscopist. Need for sedation was evaluated by asking the patient, ''Is sedation necessary for the endoscopic examination you just underwent?''

Approximately 90 percent of patients surveyed after unsedated colonoscopy or sigmoidoscopy did not feel that sedation was necessary for the examination. No significant differences were seen in pain, acceptance, need for sedation, and the rate of complete examination between patients undergoing unsedated colonoscopy and sigmoidoscopy. No complications were noted during or after the procedure in either group. Only 9.4 percent of patients in the sigmoidoscopy group and 10.8 percent of patients in the colonoscopy group considered sedation necessary for the procedure. The patient's sex and the endoscopist who performed the procedure, but not the type of procedure, were associated with severity of pain and need for sedation. Women were more likely to request or demonstrate a desire for sedation.

Researchers acknowledged some study limitations, specifically that the choice between colonoscopy or sigmoidoscopy was not random, but rather was subject to the patient's preference because the examinations were self-paid. In addition, only 14 percent of eligible patients agreed to undergo unsedated colonoscopy. It may be argued that those patients might have had a higher threshold for pain. However, they concluded that primary colorectal cancer screening with unsedated colonoscopy is feasible and may be the first-choice strategy in most Asian countries because it is more effective and may save costs and time compared with sigmoidoscopy. The researchers advise that further randomized studies comparing sedated and unsedated colonoscopy should be considered.