The National CT Colonography Trial

The National CT Colonography Trial: Multicenter Assessment of Accuracy for Detection of Large Adenomas and Cancers in a Healthy Screening Population

RATIONALE: New diagnostic procedures such as computed tomographic colonography may improve the ability to detect colorectal cancer and may provide a less invasive method of detection.

PURPOSE: This clinical trial is studying how well computed tomographic colonography works in screening healthy participants for colorectal cancer.

OBJECTIVES:

Primary

• Compare the sensitivity of computed tomographic colonography (CTC) vs colonoscopy for detecting significantly large lesions (≥ 10 mm in diameter) in asymptomatic participants, in terms of specificity, area under the ROC curve, and predictive values for detecting clinically significant colorectal neoplasia.

Secondary

• Determine the interobserver variation in accuracy of interpreting CTC examinations of these participants, including any benefits of a primary 3-dimensional read and/or independent second interpretations.
• Determine the effects of different colon preparations on the accuracy of CTC in these participants.
• Compare participant acceptance and willingness to have a repeat examination by CTC vs colonoscopy.
• Determine the accuracy of CTC in detecting flat lesions in the colon of these participants.

OUTLINE: This is a multicenter study.

Participants receive an oral laxative, oral bisacodyl, and three doses of oral barium sulphate 24 hours before imaging. After cathartic cleansing, participants undergo computed tomographic colonography followed by colonoscopy.

Participants are followed up for approximately 4 weeks.

PROJECTED ACCRUAL: A total of 2,607 participants will be accrued for this study.

1. Inclusion Criteria

   • Male or female outpatients
   • Aged 50 years or older
   • Scheduled for screening colonoscopy
   • Participant's signed informed consent

2. Exclusion Criteria

   • Symptoms of disease of the lower gastrointestinal tract, including

     • Melanotic stools or/and hematochezia on more than one occasion in the previous six months
     • Lower abdominal pain that would normally require a medical evaluation

   • Inflammatory bowel disease and/or familial polyposis syndrome

   • Serious medical conditions that would increase the risk associated with colonoscopy or are so severe that screening would have no benefit

   • Pregnancy

   • Previous colonoscopy within the past five years

   • Anemia (hemoglobin less than 10 gm/dl)

   • Positive fecal occult blood test (FOBT)