Some previous medical studies have found no significant difference in the diagnostic accuracy of CT colonography, also known as "virtual colonoscopy," and traditional optical colonoscopy. This study looks at whether both exams are as effective for adults over 65 as they are for adults between 50 and 65 years of age.
In the study, C. Daniel Johnson, M.D., professor and chair of radiology at Mayo Clinic in Scottsdale, Ariz., and a team of researchers conducted a follow-up analysis of data from the National CT Colonography Trial, in which 2,600 patients over the age of 50 underwent both virtual and optical colonoscopies at 15 centers around the country.
Dr. Johnson's team analyzed trial data from 477 patients over the age of 65 and 2,054 patients between the ages of 50 and 65 who were screened with the two procedures for clinically significant pre-cancerous growths called polyps. Patients in the study were comprised of both men and women at predominantly an average risk for colorectal cancer.
Cancerous lesions 1 centimeter or larger were found in 6.9 percent of patients in the 65 and older group and in 3.7 percent of the younger patients.
There was no significant difference in the accuracy of CT colonography for the detection of large and intermediate-sized cancers in the older participants compared to the younger participants. Sensitivity and specificity among the older and younger groups were 0.82 and 0.83 and 0.92 and 0.86, respectively.
"We found no statistical difference in the diagnostic performance between the two patient groups," Dr. Johnson said. "This is good information for patients of any age, as they can consider CT colonography as a valid option for colorectal cancer screening."
Colorectal cancer is the third most commonly diagnosed cancer in both men and women and the third leading cause of cancer deaths in the U.S. According to the American Cancer Society (ACS), a decline in colorectal cancer incidence rates over the last two decades is largely attributable to screening tests that allow polyps to be removed before they progress to cancer.
"I don't believe there is any screening test that can intervene as early in the biology of the tumor as colorectal cancer screening," Dr. Johnson said. "We have the opportunity to detect pre-malignant polyps, remove them and prevent an entire class of cancers."
Despite the effectiveness of colorectal cancer screening, the ACS estimates that only half of the U.S. population over the age 50 is being screened as recommended for the disease. Experts point to cost and a lack of access to health care as contributing factors.
Although both optical and virtual colonoscopy procedures typically require the use of laxatives to empty the colon prior to the test, there are major differences between the two exams.
In the traditional colonoscopy, an optical instrument called a colonoscope allows a physician to visually examine the colon and to remove polyps by passing a wire loop through the scope. In this procedure, the risk of perforating the bowel is higher and sedation is required.
"For the older patient, the risks of and recovery from sedation are issues," Dr. Johnson said.
Introduced in the 1990s, CT colonography produces cross-sectional, three-dimensional images of the entire colon and rectum. While the CTC exam itself is quicker to perform and about half the cost of the optical colonoscopy, it involves exposure to low doses of radiation and it must be repeated more often. When polyps 6 millimeters or larger are detected by CT colonography, the patient must undergo an optical colonoscopy to have them removed. In addition, incidental CT findings outside the colon might require additional follow-up.
"There isn't a fight between CT colonography and colonoscopy, but there is a fight in medicine against colon cancer," Dr. Johnson said. "We want patients to be screened. CT colonography is a preferred test for some patients and should be an option. Patients should talk to their doctor and choose the best option for them."
"The National CT Colonography Trial: Assessment of Accuracy in Participants Aged 65 and Older." Collaborating with Dr. Johnson were Benjamin A. Herman, S.M., Mei-Hsiu Chen, Ph.D., Alicia Y. Toledano, Sc.D., Jay P. Heiken, M.D., Abraham H. Dachman, M.D., Mark D. Kuo, M.D., Christine O. Menias, M.D., Bettina Siewert, M.D., Jugesh I. Cheema, M.D., Richard G. Obregon, M.D., Jeff L. Fidler, M.D., Peter Zimmerman, M.D., Karen M. Horton, M.D., Kevin J. Coakley, M.D., Revathy B. Iyer, M.D., Amy K. Hara, M.D., Robert A. Halvorsen Jr, M.D., Giovanna Casola, M.D., Judy Yee, M.D., Meredith Blevins, S.M., Lawrence J. Burgart, M.D., Paul J. Limburg, M.D., M.P.H., and Constantine A. Gatsonis, Ph.D.
Radiology is edited by Herbert Y. Kressel, M.D., Harvard Medical School, Boston, Mass., and owned and published by the Radiological Society of North America, Inc. (http://radiology.rsna.org/)
RSNA is an association of more than 48,000 radiologists, radiation oncologists, medical physicists and related scientists committed to excellence in patient care through education and research. The Society is based in Oak Brook, Ill. (http://www.RSNA.org)
For patient-friendly information on CT colonography, visit http://www.RadiologyInfo.org
Further Reports about: ACS > cancer screening > Colonography > colorectal cancer > colorectal cancer screening > CT colonography > optical colonoscopy > Radiological Society > rectal cancer > screening test
More articles from Health and Medicine:
Dietary amino acids improve sleep problems in mice with traumatic brain injury
12.12.2013 | Oregon Health & Science University
Orbital samples with sight-saving potential
12.12.2013 | NASA/Johnson Space Center
A unique solar panel design made with a new ceramic material points the way to potentially providing sustainable power cheaper, more efficiently, and requiring less manufacturing time.
It also reaches a four-decade-old goal of discovering a bulk photovoltaic material that can harness energy from visible and infrared light, not just ultraviolet light.
Scaling up this new design from its tablet-size prototype to a full-size solar panel would be a large step toward making solar power affordable compared with ...
Atlantische Flohkrebse pflanzen sich jetzt auch in arktischen Gewässern fort
Biologen des Alfred-Wegener-Institutes, Helmholtz-Zentrum für Polar- und Meeresforschung (AWI), haben zum ersten Mal nachgewiesen, dass sich in den arktischen Gewässern westlich Spitzbergens auch Flohkrebse aus dem wärmeren Atlantik fortpflanzen.
Diese überraschende Entdeckung deute auf einen möglichen Wandel der arktischen Zooplankton-Gemeinschaft hin, berichten die Wissenschaftler und Wissenschaftlerinnen in der Fachzeitschrift Marine Ecology ...
The molecular architecture of three key proteins and their complexes reveals how plants fine-tune their immune response to pathogens
Plants rarely get sick in their natural environment. When the threat of infection arises, a quick decision is made about the necessary countermeasures. The course is set by a protein which forms complexes with its partner proteins for this purpose.
Jane Parker from the Max Planck Institute for Plant Breeding ...
Researchers studying speciation of butterfly orchids on the Azores have been startled to discover that the answer to a long-debated question "Do the islands support one species or two species?" is actually "three species".
Hochstetter's Butterfly-orchid, newly recognized following application of a battery of scientific techniques and reveling in a complex taxonomic history worthy of Sherlock Holmes, is arguably Europe's rarest orchid species. Under threat in its mountain-top retreat, the orchid urgently requires conservation recognition.
A lavishly illustrated publication, titled "Systematic revision of Platanthera in ...
Researchers from Brown University and the University of Hawaii have found some mineralogical surprises in the Moon's largest impact crater.
Data from the Moon Mineralogy Mapper that flew aboard India's Chandrayaan-1 lunar orbiter shows a diverse mineralogy in the subsurface of the giant South Pole Aitken basin.
The differing mineral signatures could be reflective of the minerals dredged up at the time of the giant impact 4 billion years ago, ...
12.12.2013 | Life Sciences
12.12.2013 | Earth Sciences
12.12.2013 | Studies and Analyses
11.12.2013 | Event News
10.12.2013 | Event News
05.12.2013 | Event News