Latest research examines colorectal cancer risk factors

New research being presented at Digestive Disease Week® (DDW) looks at patient experiences with colorectal cancer screening and questions current screening guidelines. Worldwide, colorectal cancer is the second most common cancer in women and the third most common in men. Studies found that patients prefer colonscopy over computed tomography colonography, despite the former’s more invasive nature, and highlight the importance of a patient’s experience and role in the process of colonoscopy. Other research assesses the benefits of colorectal cancer screening for the elderly and persons with type II diabetes, and indicates a prevalence rate for pre-cancerous adenoma (benign tumor or polyp) that is higher than previously thought.

“These findings could affect thinking about who should be screened for colorectal cancer and how, as well as when,” said John Petrini, MD, FASGE, FACP, Sansum Clinic, Santa Barbara, CA. “Findings like these are critically important since early detection is the key to reducing colorectal cancer deaths.” DDW is the largest international gathering of physicians and researchers in the field of gastroenterology, hepatology, endoscopy and gastrointestinal surgery.

Patient Satisfaction and Preferences: Colonoscopy or Computed Tomography Colonography for Colorectal Cancer Screening (Abstract #445)

Patients in a recent study were more satisfied with colonoscopy than computed tomography colonography (CTC), even though CTC is less invasive and takes less time than colonoscopy, according to new research from the University of British Columbia, Vancouver, Canada. Patient satisfaction is believed to be an important factor in determining uptake and compliance with any screening test, so investigators sought to compare patient satisfaction following both CTC and colonoscopy.

Researchers led by Greg Rosenfeld, MD, at the University of British Columbia, conducted a study comparing same-day CTC and colonoscopy among 90 subjects aged 50 and older who were at average risk for colorectal cancer (CRC). Overall, patients felt that colonoscopy was more satisfactory — they were less anxious with colonoscopy than with CTC and reported that, although their pain was adequately controlled in both procedures, there was less pain during colonoscopy. Typically, a colonoscopy is approximately 30 minutes and a CTC is five to 10 minutes in duration. Dr. Rosenfeld said researchers were surprised by the findings. Investigators expected patients to prefer CTC due to its shorter duration, minimal discomfort and the lack of requirement for sedation; patients were not restricted from activities such as driving after CTC, as is necessary after a colonoscopy performed under sedation.

CTC has not seen the growth initially anticipated when the test was first introduced for a variety of reasons, according to Dr. Rosenfeld. As was found in this study, the accuracy of the test in detecting adenomatous polyps does not appear to be as high as previously reported. There are also some concerns about radiation exposure, as well as polyps that are found and still require colonoscopy for removal. The end result is that in Canada, CTC is not widely used for CRC screening of average-risk individuals.

Dr. Rosenfeld cautioned that people should not assume from these findings that CTC is not a useful test or that it is uncomfortable. “Patients are willing to do it, they just prefer the colonoscopy. Certainly, CTC still has a role. However, our research suggests that colonoscopy is the preferred test for screening average-risk patients,” he said.

Colonoscopy is the examination of the large bowel using a camera scope inserted through the anus, while CTC utilizes a CT scanner to produce a 3D image of the abdomen, enabling visualization of the colon. CTC is an alternative to colonoscopy, which is the most commonly used test for CRC screening in patients who are at average risk of developing colon cancer. Average-risk individuals are those people over the age 50 with no personal or family history of CRC.

In order to assess satisfaction, patients completed an 11-question survey immediately after having a CT scan. Then after undergoing a colonoscopy, patients filled out another similar questionnaire prior to being discharged from the hospital. Finally, a random quarter of the patients received the same questionnaires two to eight weeks later in the mail to assess the reliability of their responses. The questionnaires included questions about anxiety and comfort during the procedures, skills and personal manner of the person administering the procedure, and overall satisfaction and preferred choice of screening modality in the future.

Additionally, researchers assessed readers with varying levels of experience to determine how they performed in interpreting the CTC scans. The accuracy of CTC in detecting adenomatous polyps greater than 6 millimeters was compared with colonoscopy. Adenomatous polyps — small growths in the colon that are the precursors of colon cancer — are the target of screening programs, as early detection and removal prevents the progression to cancer.

No pharmaceutical funding was received for this study.

George Ou, MD, will present these data on Sunday, May 20 at 10:30 a.m. PT in Room 4 of the San Diego Convention Center.

Gender Trends in Adenoma Detection: Should the Guidelines for ADR Change? (Abstract #798)

Adenomas appear to be more prevalent than previously thought in both females and males, according to new research from the Mayo Clinic, Jacksonville, FL. As part of a large study to improve adenoma detection, investigators led by Susan Coe, MD, third year gastroenterology fellow with Mayo Clinic, looked at gender trends in adenoma detection rates among average-risk screening patients.

They found that the adenoma detection rate for average-risk females was 25 percent, while the rate for average-risk males was 41 percent. Current guidelines say there should be 15 percent adenoma detection in females and 25 percent in males.

Dr. Coe said these findings are instructive because they strongly suggest that the current guidelines need to be reassessed and increased for both genders. Although males are more likely to have adenomas and to develop colorectal cancer, the risk for advanced adenomas in female and male patients with adenomas is about the same.

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