Mar. 14, 2003 St. Louis, March 13, 2003 -- Surveying patients who were screened for colorectal cancer, investigators at the Siteman Cancer Center at Washington University School of Medicine and Barnes-Jewish Hospital in St. Louis found that most prefer "virtual" colonoscopy to traditional screening, but most had positive appraisals of both. Patients didn't, however, like the bowel preparation prior to either screening test.
The researchers report their findings in the March issue of the American Journal of Gastroenterology.
"Colorectal cancers are very preventable and treatable," says Stephen L. Ristvedt, Ph.D., assistant professor of medical psychology in psychiatry at Washington University and lead author of the study. "But many people don't get screened, and we want to understand what the barriers are."
Although about 90 percent of colorectal cancers and deaths are thought to be preventable, colorectal cancer is the second leading cause of cancer-related deaths in the United States among both men and women. It is more deadly than either prostate cancer or breast cancer and only ranks behind lung cancer in mortality.
Screening tests can identify the disease in its earliest stages when small growths called polyps can be found and removed before they become cancerous. Because there often are no symptoms associated with pre-cancerous polyps, regular screening is key to reducing mortality.
"Colorectal cancer remains a leading cause of cancer-related death because patients are reluctant to be screened," says co-investigator Elizabeth G. McFarland, M.D., associate professor of radiology at the Mallinckrodt Institute of Radiology at Washington University.
During standard colonoscopy, a camera is inserted into the colon through the rectum, allowing physicians to visualize and remove any growths. Because of the invasive nature of the test, patients are sedated.
During virtual colonoscopy, also known as CT colonography, patients remain awake and alert and are asked to hold their breath for 10 to 20 seconds while computed tomography (CT) images of the colon are taken. This procedure is for screening purposes only. If polyps are found, a colonoscopy or other procedure is required to treat them.
Although the virtual test does not require the insertion of a camera, it does require that air be pumped into the rectum to inflate the colon. Some patients reported that this experience was unpleasant.
Because CT colonography is less invasive than traditional procedures and requires no sedation, McFarland has been leading an effort to compare its accuracy with standard colonoscopy, the current "gold standard" in colorectal screening. If it proves to be as accurate at detecting polyps, its less-invasive nature might encourage more people to get screened.
The study included 120 patients who underwent a CT colonography followed by a traditional colonoscopy on the same day. Patients completed surveys about the screening tests at three different times: just prior to the CT colonography, between the CT test and the colonoscopy and again two to three days after the procedures.
"We asked what they expected in terms of pain, embarrassment and difficulty," Ristvedt says. "Before the procedures, patients expected more pain with colonoscopy than with CT, but afterward many reported there actually was less pain and embarrassment for colonoscopy because they had been sedated and given pain medications during that procedure."
However, almost 58 percent of patients said they would prefer CT colonography in the future. Fourteen percent would rather have a colonoscopy, and 34 percent had no preference.
Patients reported little pain, difficulty or embarrassment for either procedure, and most agreed that the advance bowel preparation required for both procedures was unpleasant.
"Of all of the issues surrounding these tests, bowel preparation seems to be the greatest barrier to compliance for colorectal screening," McFarland says. "Patients can't eat what they normally eat, and they have to drink a large volume of a liquid that helps to cleanse their colon."
The liquid nauseates some patients. Others lose electrolytes and become weak from the cleansing process. Currently, the preparation is essential for both tests.
"Certain techniques in development may change that in the future," McFarland says. "But for now, we have to be concerned that colorectal cancer is a leading cause of cancer-related death because of non-compliance with screening. What makes it so tragic is that if you detect the disease early, you can prevent it. And right now, many patients are reluctant to get screened."
Ristvedt SL, McFarland EG, Weinstock LB, Thyssen EP. Patient preferences for CT colonography, conventional colonoscopy and bowel preparation. The American Journal of Gastroenterology, vol. 98:3, pp. 578-585, March, 2003.
This research was supported by grants from the National Cancer Institute of the National Institutes of Health.
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