Public Release: 

Latest research examines colorectal cancer risk factors

Health outcomes explored at DDW® 2012

Digestive Disease Week

San Diego, CA (May 22, 2012) -- 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.

They also sought to understand the features of the adenomas they were finding and how they may differ between genders. They found that in patients with adenomas, there was no statistical difference between males and females in adenomas that were large, flat, contained advanced histology or were located in the right colon -- all features associated with an increased risk of colorectal cancer (CRC). The researchers reviewed data from 2,400 colonoscopies and focused on average-risk patients who were undergoing CRC screenings. (Average-risk means someone who has never had polyps and does not have a family history of CRC.)

Dr. Coe suggested it might be feasible to adjust guidelines to provide benchmarks for the detection of advanced adenomas. However, investigators do not truly know what the upper limit of detection is, so while rates are improving, investigators are unsure how many adenomas can feasibly be detected overall. While benchmarks serve as an important quality target, there still may be considerable room for improvement.

She added that there is a lot of exciting technology on the horizon centered on methods of detecting advanced adenomas and CRC. "It will be interesting to see how these tests complement and improve colorectal cancer screening in the future," she stated.

Dr. Coe expects that next steps will look at gender differences in the detection rate of serrated polyps. "These polyps, which tend to be subtle, large, flat, hyperplastic-appearing polyps in the right colon, may account for at least some of the cancers that later develop after a negative screening colonoscopy."

No pharmaceutical funding was provided for this study.

Dr. Coe will present these data on Monday, May 21 at 3 p.m. PT in Room 4 of the San Diego Convention Center.

Patient Perception of Bowel Preparation for Colonoscopy is Associated with the Quality of Preparation (Abstract #Tu1737)

A patient's perceived experience with bowel preparation predicts the cleanliness of the colon and the detection of polyps during colonoscopy, according to new research from California Pacific Medical Center, San Francisco. Previous studies have shown a link between the quality of bowel preparation and the detection rate for pre-cancerous adenomas. In this study, researchers sought to determine how certain patient-related factors might also affect the detection of polyps, which decreases the risk of colorectal cancer.

With this in mind, investigators led by Edward W. Holt, MD, gastroenterology fellow at California Pacific Medical Center, surveyed 430 patients immediately prior to colonoscopy to learn how much of the bowel prep they thought they had completed, how clear their bowel movements were after the prep, and their impression of the overall tolerability of bowel preparation. The actual cleanliness of the colon and the adenoma detection rate were then measured during colonoscopy.

Results showed that 94 percent of participants reported completing at least 95 percent of the preparation, 97 percent reported completely liquid bowel movements after prep, and 21 percent rated their experience with the bowel prep as "good." Patients who gave their prep a favorable rating by any of these three criteria were found to have significantly cleaner colons during colonoscopy -- at colonoscopy, 87 percent of the bowel preps were scored as excellent. Furthermore, patient-perceived tolerability of bowel preparation was independently associated with what was found during colonoscopy: patients who reported the worst experience with bowel preparation had significantly lower rates of adenoma detection.

Dr. Holt believes that results of this study raise the possibility that colonoscopy may be more effective when providers take extra time to explain the bowel preparation process and to set realistic expectations for patients. If a patient is not physically or mentally prepared for the prep, does not know how it can be made more tolerable or does not understand why the prep is such an important part of the colonoscopy, then he or she may benefit less from the procedure, in addition to walking away unhappy.

He cautioned against inferring from this research that improving the patient's experience with bowel preparation will guarantee the detection of more polyps and a lower risk of death from colon cancer. He emphasized that this study highlights the importance of the patient's experience and role in the process of colonoscopy for colon cancer screening. However, many factors influence the effectiveness of colonoscopy as a screening tool, including how soon it is performed post-bowel prep, how long the procedure takes and the cleanliness of the colon.

The study does not account for why the patient's experience may be so important, but there are several possibilities. In particular, if the taste or the sheer volume of bowel prep causes a patient to drink less of it, it could prevent adequate cleansing of the colon, making it harder for the physician to detect polyps.

"If the bowel prep experience is intolerable for the patient, it could have implications beyond the time when the patient is actually trying to drink the prep -- it may hinder our ability to detect polyps during the colonoscopy," said Dr. Holt. "Putting more emphasis on a better patient experience may be another way to increase the possibility of removing pre-cancerous polyps."

Dr. Holt will present these data on Tuesday, May 22 at noon PT in Halls C-G of the San Diego Convention Center.

First Time Colonoscopy in the Elderly Yields a High Rate of Curable Colorectal Cancer (Abstract #728)

Colonoscopy finds a high rate of colorectal cancer (CRC) in elderly patients who had not been previously screened, according to new research from Spectrum Health, Grand Rapids, MI. Because of the considerable variation in health and functionality among elderly individuals, investigators led by Therese G. Kerwel, MD, research fellow at Grand Rapids Medical Education Partners/Spectrum Health, sought to determine cancer detection rates in the elderly undergoing outpatient colonoscopy. The results were stratified according to when the most recent colonoscopy was performed.

Researchers identified 903 outpatient exams in elderly patients over a two-year period. They looked at why these individuals were undergoing colonoscopy and assessed results for cancer diagnoses. Investigators found that elderly patients who had never previously undergone a colonoscopy had a cancer rate of 9.4 percent, which was significantly higher than those who had previously undergone colonoscopy. Furthermore, the patients with identified CRC all underwent curative surgery. The cancers had not yet metastasized, making screening even more important, Dr. Kerwel said.

"It is worthwhile to offer a screening colonoscopy for elderly patients in good health and functional status who have never previously undergone the test," Dr Kerwel said. She added that to address efficient utilization of resources along with costs, instead of completely stopping screening, providers should consider reducing the number of surveillance exams in this population since these had very low yield for detection of cancer, and the detection of polyps in this population is of questionable significance.

The use of screening colonoscopy in the elderly has become controversial in recent years with the U.S. Preventive Services Task Force recommendation against routine screening in adults aged 76 to 85. The task force has determined that the risks outweigh the benefits and that the life years saved by screening this population become so reduced that it does not justify the risk. Additionally, a lack of Medicare reimbursement has served as a financial disincentive to screen elderly patients.

Dr. Kerwel will present these data on Monday, May 21 at 2:21 p.m. PT in 28ab, San Diego Convention Center.

Should Diabetes Mellitus be an Indication for Earlier Colorectal Cancer Screening? (Abstract #Tu1185)

A new study from the Washington University School of Medicine, St. Louis, MO, suggests that patients with diabetes mellitus type II (DM) should be screened for colorectal cancer (CRC) at younger ages than is usually recommended. While DM, which occurs when there are excess levels of insulin in the blood, is associated with increased risk of colorectal neoplasia (new tissue that results in the formation and growth of a tumor), there are currently no modifications in current screening guidelines for individuals with DM.

Investigators led by Hongha T. Vu, MD, clinical gastroenterology fellow, Washington University, sought to determine if patients with DM should be screened earlier than patients at average risk for CRC. They found that the presence of adenomas among those screened between the ages of 40 and 49 with DM was about the same as those screened between the ages of 50 and 59 without DM. While many studies show an association between diabetes and CRC and polyps, this is the first study to show adverse risk in younger patients demonstrating that they should undergo screening earlier.

"We concluded that those with diabetes may require early screening because they have a similar risk of colon cancer and precursor adenomas as older non-diabetics who are currently recommended to start screening at age 50," said Dr. Vu.

Researchers performed a retrospective cohort study of patients undergoing colonoscopy over a six-year period and compared three age groups matched for date of exam and gender: ages 40 to 49 with DM, ages 40 to 49 without DM, and ages 50 to 59 without DM.

Dr. Vu cautioned that because the study was not prospective, investigators cannot say with certainty that diabetes is by itself a risk factor. Other risk factors overlap, such as obesity, diet and smoking. She added that the public health implications are significant since approximately 23 million Americans have diabetes, and that number is expected to double in the next 25 years.

No pharmaceutical funding was provided for this study.

Dr. Vu will present these data on Tuesday, May 22 at noon PT in Halls C-G of the San Diego Convention Center.


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, the American Gastroenterological Association (AGA) Institute, the American Society for Gastrointestinal Endoscopy and the Society for Surgery of the Alimentary Tract, DDW takes place May 19󈞂, 2012, at the San Diego Convention Center. The meeting showcases more than 5,000 abstracts and hundreds of lectures on the latest advances in GI research, medicine and technology. For more information, visit

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