National Computed Tomography Colonography Trial

Website: http://imaging.cancer.gov/clinicaltrials/screening

Principal Investigator:
C. Daniel Johnson, M.D., Mayo Clinic

Approximately 145,290 Americans will be diagnosed with colorectal cancer in 2006. This is the second most common cause of cancer death in the United States. As most colon cancers develop from polyps, detection and removal of these polyps can prevent cancer. When colon cancer is detected in its early stages, the survival rate is 90 percent. Though there are several approved screening tests for colon cancer, including colonoscopy, many people have never been screened or are screened inconsistently. The reasons are multifaceted, including insurance coverage, access to screening, and patient discomfort during or before screening procedures.

Traditional, or optical, colonoscopy is an examination of the entire colon (large bowel) using a lighted instrument called a colonoscope, which is inserted through the rectum while the patient is sedated or under anesthesia. Potential risks of colonoscopy include bleeding and puncturing of the lining of the colon. A new form of colonoscopy, called CT colonography and commonly known as virtual colonoscopy, allows physicians to use cutting-edge imaging technology to produce three- dimensional X-ray images of the colon without probing inside the body. This minimally invasive technique requires less time than traditional colonoscopy, does not necessitate sedation, and is less expensive— all characteristics that may entice people to be screened for colon cancer.

It is not yet known, however, whether CT colonography is as effective as traditional colonoscopy in detecting polyps and cancer. As leaders in evaluating new imaging technologies, CIP and ACRIN initiated the National CT Colonography Trial at 15 sites across North America. ACRIN, a national network of radiologists funded by CIP, is coordinating the study, which has recruited more than half the 2300 individuals needed for the trial since it opened in February 2005.