"Colonoscopies are extremely important preventive methods against colon cancer. Less-invasive screening tests may be preferable to patients and could help us reduce the colorectal cancer death rate because of increased screening for the disease," said Bernard Levin, M.D., from the University of Texas M.D. Anderson Cancer Center. "It's important to ensure that non-invasive colorectal screening tests are accurate before recommending their wide-spread use. Right now, virtual colonoscopy, stool DNA testing and new, fecal immunochemical tests are promising, but require additional technological refinements."
Multicenter Prospective Comparison of Colon Imaging Tests (Abstract 100606*)
New technologies are becoming available to perform colonic tests in alternative fashions. In a study funded by the National Cancer Institute and conducted at the Duke Clinical Research Institute, researchers found that colonoscopy fairs better than other imaging tests in an overall comparison of accuracy, cost and patient acceptance.
Colonoscopy (C) is generally considered to be the optimal method for colon evaluation, but in practice other imaging tests, including the air contrast barium enema (ACBE) and computed tomographic colonography (CTC), are also used. In this study, fourteen sites recruited patients with an increased need for colon examination to undergo each of the three procedures due to fecal occult blood (FOB), hematochezia (blood in the stool), iron deficiency anemia, or a family history of colon cancer. ACBE was performed seven to 14 days prior to C and CTC (performed on the same day), with a primary outcome of sensitivity compared to a consensus colon examination for the detection of colon cancers and polypoid lesions (polyps) greater than or equal to one centimeter in diameter (significant lesions). The prevalence of colon cancer or the specified lesions in this patient population was 10.3 percent (63/614 patients).
The sensitivity point estimates for the three imaging tests for lesions greater than or equal to 10 millimeters were 0.48 (ACBE), 0.59 (CTC) and 0.98 (C); the differences between ACBE and CTC were statistically significant. The specificity point estimates were 0.90 (ACBE), 0.96 (CTC), and 1.00 (C).
"As patients undergo these screening procedures, it is important to be confident in the accuracy of the test, as colon cancer is a significant cause of death that may, in some cases, be preventable," said Don Rockey, M.D., lead author of the study. "Based on these findings, colonoscopy is significantly more accurate than either the ACBE or CTC procedures. But it is important to note that technologies are rapidly evolving and CTC is likely to improve."
Experimental and Clinical Studies of Wireless Capsule Colonoscopy (Abstract 101749*)
Colon screening can be challenging for some patients and barriers to a complete exam can lead to inaccuracies and misdiagnosis. To quell these barriers, scientists from St. Mary's Hospital in London used a capsule endoscopy as an adjunct to conventional colonoscopy and yielded significant results. Barriers to accurate screenings often include cleanliness, slow transit times, intermittent rapid movements, larger diameter lumen (the cavity of the intestine) and capsule transmission times.
Researchers viewed colonic images in 38 patients with obscure gastrointestinal bleeding, obtained without preparation using Given Imaging M2A capsules with a seven-hour life. An additional 34 patients took colonic preparation and were studied with the capsule. In 13 of these patients, long-play (LP) capsules with a potential transmission time of 10 hours were used and in 21, short-play (SP) capsules with a two-hour delay were tested. Fourteen patients were tested with seven LP and seven SP capsules.
In 38 clinical studies performed without colonic preparation, 35 had interpretable colonic images. Both the LP and SP capsules used with colonic preparation increased the number of interpretable colonic images compared with M2A. LP capsules used with colon prep reduced oro-anal transit and colo-anal transit times. Comparing SP and LP, oro-anal transit time and colon passage time were both reduced using SP. In clinical studies of 14 patients, the researchers revealed missed colon cancer, bleeding Meckel's diverticulum (a small pouch extending from the wall of the intestine and located in the lower portion of the small intestine), occult Crohn's disease, missed colonic polyps and angiodysplasia, or colonic bleeding due to deteriorating blood vessels in the colon walls.
"Capsules used in patients with incomplete colonoscopies have provided useful clinical diagnostic information," said Paul Swain, M.D., lead author of the study. "Just as combined therapies have done, combination screening procedures may lead to improved early diagnosis and survival rates against colon cancer."
Major Advances in Colonoscopic Technology: The ColonoSight®, a Pull-Power Assisted Disposable, Non Fiber-Optic Colonoscope (Abstract 102221*)
The introduction of the colonoscopy procedure was a major advance in the diagnosis and prevention of colorectal cancer and other colonic diseases. However, the technology has progressed very little over the last few years and has several disadvantages, including the need for disinfection of the equipment between procedures, high costs for equipment repair and the need to push the instrument from outside the patient to advance in the colon. This can cause significant discomfort for the patient, stretches the colon and increases the risk of perforation.
An FDA-approved novel device, the ColonoSight, addresses these issues. The device was developed and tested by researchers from Memorial Sloan-Kettering Cancer Center, centers in Italy and the Sightline Corporation from Israel. The ColonoSight uses air pressure-assisted pull technology that incorporates a disposable system. The pneumatic mechanism generates a forward force just below the tip of the scope, which pulls the scope while the operator navigates with the handles, drastically reducing the need to push the instrument.
Simultaneously, the equipment deploys a protective disposable sheath as the scope advances in the colon, which incorporates disposable work channels, eliminating the need for disinfection between procedures while at the same time reducing the instrument downtime and possibly the risk of infection. The equipment also uses integrated LED (light emitting diode) as a light source in the tip of the scope, eliminating the need for fiber-optics and reducing repair costs.
A complete screening or therapeutic colonoscopy was attempted in 72 patients with the ColonoSight. The success rate in reaching the cecum (the beginning of the large intestine) was 88 percent, at an average rate of 12.3 +/- 7 minutes, though in nine patients it was reached in less than five minutes. There were no complications during the procedures or for the following two-week period.
Bacteriological cultures obtained post-procedure from various areas of the equipment protected by the sheath showed that the barrier was effective in protecting the non-disposable components.
"According to our findings, the three unique functions of the ColonoSight - disposability, power-assisted advancement and integrated LED illumination - function well and safely," said Moshe Shike, M.D., lead author of the study. "We believe this could be an important breakthrough in improving the costs, function and operation of the endoscopic examination of the colon."
Digestive Disease Week (DDW) is the largest international gathering of physicians, researchers and academics in the fields of gastroenterology, hepatology, endoscopy and gastrointestinal surgery. Jointly sponsored by the American Association for the Study of Liver Diseases (AASLD), the American Gastroenterological Association (AGA), the American Society for Gastrointestinal Endoscopy (ASGE) and the Society for Surgery of the Alimentary Tract (SSAT), DDW takes place May 15-20, 2004 in New Orleans, Louisiana. The meeting showcases approximately 5,000 abstracts and hundreds of lectures on the latest advances in GI research, medicine and technology.
*Abstract numbers listed above correlate to abstract ID numbers listed on the DDW Web site, www.ddw.org. They do not coincide with program numbers as found in the printed DDW Program Guide.