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
Portable finger-probe device can successfully measure liver function in potential organ donors
29.05.2015 | University of California - Los Angeles Health Sciences
Project start: New active substance targeting dreaded hospital pathogens
29.05.2015 | Deutsches Zentrum für Infektionsforschung
Many joining and cutting processes are possible only with lasers. New technologies make it possible to manufacture metal components with hollow structures that are significantly lighter and yet just as stable as solid components. In addition, lasers can be used to combine various lightweight construction materials and steels with each other. The Fraunhofer Institute for Laser Technology ILT in Aachen is presenting a range of such solutions at the LASER World of Photonics trade fair from June 22 to 25, 2015 in Munich, Germany, (Hall A3, Stand 121).
Lightweight construction materials are popular: aluminum is used in the bodywork of cars, for example, and aircraft fuselages already consist in large part of...
Using ultrashort laser pulses, scientists in Max Planck Institute of Quantum Optics have demonstrated the emission of extreme ultraviolet radiation from thin dielectric films and have investigated the underlying mechanisms.
In 1961, only shortly after the invention of the first laser, scientists exposed silicon dioxide crystals (also known as quartz) to an intense ruby laser to...
The only professorship in Germany to date, one master's programme, one laboratory with worldwide unique equipment and the corresponding research results: The University of Würzburg is leading in the field of biofabrication.
Paul Dalton is presently the only professor of biofabrication in Germany. About a year ago, the Australian researcher relocated to the Würzburg department for...
Physicists have developed an innovative method that could enable the efficient use of nanocomponents in electronic circuits. To achieve this, they have developed a layout in which a nanocomponent is connected to two electrical conductors, which uncouple the electrical signal in a highly efficient manner. The scientists at the Department of Physics and the Swiss Nanoscience Institute at the University of Basel have published their results in the scientific journal “Nature Communications” together with their colleagues from ETH Zurich.
Electronic components are becoming smaller and smaller. Components measuring just a few nanometers – the size of around ten atoms – are already being produced...
Development and implementation of an advanced automobile parking navigation platform for parking services
To fulfill the requirements of the industry, PolyU researchers developed the Advanced Automobile Parking Navigation Platform, which includes smart devices,...
20.05.2015 | Event News
18.05.2015 | Event News
12.05.2015 | Event News
29.05.2015 | Life Sciences
29.05.2015 | Earth Sciences
29.05.2015 | Physics and Astronomy