Large, Multi-Center Trial Demonstrates Comparable Accuracy for Virtual Colonoscopy and Standard Colonoscopy
Computerized tomographic (CT) colonography, also known as virtual colonoscopy,
is comparable to standard colonoscopy, which uses a long, flexible tube with
a camera to view the lining of the colon, in its ability to accurately detect
cancer and precancerous polyps and could serve as an initial screening exam
for colorectal cancer, according to the results of the American College of
Radiology Imaging Network (ACRIN) National CT Colonography Trial.
CT colonography employs virtual reality technology to produce a three-dimensional
visualization that permits a thorough and minimally invasive evaluation of
the entire colon and rectum. The ACRIN trial, sponsored by the National Cancer
Institute (NCI), part of the National Institutes of Health (NIH), enrolled
more than 2,600 patients at 15 sites nationwide. It is the largest multi-center
study to compare the accuracy of state-of-the-art CT colonography to the gold
standard of conventional colonoscopy. The results of this study are published
in the Sept. 18, 2008, issue of the New England Journal of Medicine.
"CT colonography could be adopted into the mainstream of clinical practice as a primary option for colorectal cancer screening. We hope that this additional, less-invasive option for cancer screening will lead more people to get screened and will ultimately result in fewer deaths from colorectal cancer," said ACRIN National CT Colonography Trial principal investigator C. Daniel Johnson, M.D., of the Mayo Clinic in Scottsdale, Ariz.
Colorectal cancer is the third most frequently diagnosed cancer and second leading cause of cancer death in men and women in the United States. Although screening recommendations vary somewhat, many recommend that adults aged 50 and older in the general population receive a colonoscopy every 10 years or more frequently, depending on known risk factors. Yet, despite the known benefits of screening, studies indicate that the majority of Americans age 50 and older are not being screened for the disease.
"Imaging advances such as virtual colonoscopy are an important step forward that could potentially increase the number of people who would agree to be screened. We hope, through continued imaging research and the development of molecular diagnostic techniques, that we will continue to improve our screening options in the years ahead and, as a result, continue to see a decline in the incidence of colorectal cancer," said NCI Director John E. Niederhuber, M.D.
"Previous single-site studies had indicated that CT colonography held promise in screening for colorectal cancer due to its accuracy, safety, cost-effectiveness, and patient acceptability. However, validation of the technique across multiple centers and radiologists was needed to provide more evidence of the exam’s viability. The ACRIN trial has now validated that CT colonography could serve as an initial screening exam for the population in which screening is indicated," said Mei-Hsiu Chen, Ph.D., trial statistician, ACRIN Biostatistics and Data Management Center, Brown University, Providence, R.I.
In the ACRIN trial, the CT colonography findings were evaluated using standard colonoscopy as the reference standard. CT colonography was found to be highly accurate for the detection of intermediate and large polyps. Ninety percent of the polyps 1 centimeter or larger were detected by CT colonography. Even polyps as small as one half centimeter were detected by CT colonography with a high degree of accuracy. Since most colon cancers develop from polyps, and screening to find and remove these polyps can prevent colon cancer, an opportunity exists to save lives with early detection.
"There are clearly clinical settings in which CT colonography, colonoscopy, or both tests in combination offer distinct advantages. The most important advice we can give to patients is to get screened. How they get screened should be an individual decision based upon discussions between patients and their providers," said gastroenterologist and study author Paul Limburg, M.D., Mayo Clinic in Rochester, Minn.
Study participants had to be at least 50 years old, scheduled for a screening colonoscopy, and not have received a colonoscopy in the past five years. Each participant had a CT colonography followed by a colonoscopy, with 99 percent of both exams accomplished on the same day. Participants scheduled for a screening colonoscopy were recruited with assistance from gastroenterologists at each participating site. Preparation for CT colonography and colonoscopy both involve taking solutions to clear and cleanse the colon.
Research advocates played an important role in advising the scientists who conducted this study. "As the ACRIN patient advocate who worked with the research team and as a research advocate with C3: Colorectal Cancer Coalition, I am pleased that CT colonography can be added to the list of screening options. Having a method that is accurate and comprehensive while being minimally invasive is needed if we are to succeed in substantially reducing deaths from colorectal cancers," said Pam McAllister, Madison, Wis.
For more information regarding colorectal cancer, please visit the National Cancer Institute at:
For a Q&A on this trial, please go to: http://www.cancer.gov/newscenter/pressreleases/VirtualColonoscopyQA.
For further information about the ACRIN National CT Colonography
Trial, please visit: http://www.acrin.org/TabID/151/Default.aspx.
To arrange an interview with Dr. Johnson, please contact the American
College of Radiology (ACR) Public Relations manager, Shawn Farley,
at 703-648-8936 or firstname.lastname@example.org.
ACRIN is a NCI Clinical Trials Cooperative Group. It is made up
of investigators from over 100 academic and community–based medical facilities in the United States and several international institutions. ACRIN’s
mission is to develop information, through clinical trials of diagnostic
imaging and image-guided therapeutic procedures that will result
in: 1) the earlier diagnosis of cancer, 2) allaying the concerns
of those who do not have cancer, and 3) improving the length and
quality of lives of cancer patients. Further information about
ACRIN can be found at www.acrin.org.
The American College of Radiology (ACR) is a national professional
organization serving more than 32,000 diagnostic radiologists,
radiation oncologists, interventional radiologists, nuclear medicine
physicians, and medical physicists, with programs focusing on the
practice of radiology and the delivery of comprehensive health
NCI leads the National Cancer Program and the NIH effort to dramatically
reduce the burden of cancer and improve the lives of cancer patients
and their families, through research into prevention and cancer
biology, the development of new interventions, and the training
and mentoring of new researchers. For more information about cancer,
please visit the NCI Web site at http://www.cancer.gov or call
NCI's Cancer Information Service at 1-800-4-CANCER (1-800-422-6237).
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.