Inclusion Criteria

DISEASE CHARACTERISTICS: The following case material must be submitted for each patient:
No colonic diseases except polyps, cancer, or diverticulosis Optimal diagnostic
computerized tomographic colonography (CTC) data with computed tomography acquisition
parameters that meet the following minimal standards: Slice thickness no greater than 5 mm
Reconstruction interval no greater than 3 mm Pitch no greater than 2 Anatomic coverage of
the entire colorectum Supine and prone data sets Complete colonoscopy performed within 30
days following CTC by a board certified gastroenterologist or a physician with at least 3
years of colonoscopic experience Pathology reports for all endoscopically or surgically
removed colorectal lesions with the exception of polyps that are inadvertently dropped at
the time of retrieval Photograph or videotape record of dropped lesion allowed as proof of
its existence All studies are allowed including those with lesions less than 1 cm, lesions
at least 1 cm, or no lesions Report documents size, site, stage, grade, and type of
colorectal cancers; size, site, degree of dysplasia, and type of colorectal adenomas; and
types of other lesions (e.g., inflammatory, vascular, ulcerative) Demographic data
including patient's age, sex, ethnic background, symptoms, risk factors, and relevant
clinical history

PATIENT CHARACTERISTICS: Age: 18 and over Performance status: Not specified Life
expectancy: Not specified Hematopoietic: Not specified Hepatic: Not specified Renal: Not
specified

PRIOR CONCURRENT THERAPY: See Disease Characteristics