VCU news

By Anne Buckley

Computed Tomographic (CT) Colonography, also known as virtual colonoscopy, is shown to have high accuracy in its ability to detect cancer and precancerous polyps using conventional colonoscopy as the gold, or reference, standard and could serve as a primary screening option for colorectal cancer, according to the results of the American College of Radiology Imaging Network (ACRIN) National CT Colonography Trial. 

The ACRIN trial, sponsored by the National Cancer Institute (NCI), part of the National Institutes of Health (NIH), was conducted at VCU and 14 other sites.  It is the largest multi-center study to estimate the accuracy of state-of-the-art CT colonography involving 117 participants at VCU and 2,600 participants total nationwide.
 
“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.

CT colonography employs cutting edge, virtual reality technology to produce three-dimensional images that are viewed as a video of the inside of the colon and permit a thorough and minimally invasive evaluation of the entire colorectal structure. The results of this study are published in the September 18 of the New England Journal of Medicine.

“From a radiologist’s point of view, when I’m reading a study, I’m flying through the patient’s colon on a computer in a fashion similar to playing a computer game of a flight simulator,” said Robert A. Halvorsen, Jr., M.D., professor of radiology and director of Quality Assurance in the VCU School of Medicine. “These results provide evidence that CT colonograpy is approximately as successful as standard colonoscopy in the detection of colonic polyps. “It also is much easier for patients, does not require the patient to be sedated, miss a full day of work, or have someone to drive them home,” he said.

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. 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.

“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 insight about the exam’s viability. The ACRIN trial has now validated that CT colonography could serve as a screening exam for the population in which screening is indicated,” said Mei-Hsiu Chen, PhD, trial statistician, ACRIN Biostatistics Center, Brown University, Providence, R.I.
   
In the ACRIN trial, the CT colonography findings were evaluated using conventional 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 half a centimeter were detected by CT colonography with a high sensitivity. 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.

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 same-day colonoscopy. 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 cleanse the colon.
   
“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 further information about the ACRIN National CT Colonography Trial, please visit: http://www.acrin.org/TabID/151/Default.aspx.

About ACRIN:
ACRIN is an NCI-sponsored clinical trials cooperative group made up of investigators from over 100 academic and community-based facilities in the United States, and several abroad.  Its broad goal is to establish imaging as an important tool in the development and monitoring of targeted interventions for cancer treatment and prevention.  ACRIN is under the leadership of Network Chair Mitchell Schnall, MD, PhD and Constantine Gatsonis, PhD the Network Statistician.  The administrative office is headquartered at the Philadelphia, PA, office of the American College of Radiology a national professional organization serving more than 32,000 diagnostic radiologists, radiation oncologists, interventional radiologists, nuclear medicine physicians, and medical physicists.  The ACRIN Biostatistics Center is located at Brown University in Providence, R.I. The NCI component of the ACRIN Cooperative Group is administered by the Cancer Imaging Program within NCI’s Division of Cancer Treatment and Diagnosis.  For more information visit www.acrin.org.