Primary Hypothesis: Risk factors can be determined for large (>1 cm) adenomas, precursor lesions for colorectal cancer. Secondary Hypothesis: Determine long-term rates for development or recurrence of polyps; determine sensitivity/specificity of current colon cancer screening strategies; determine relationship of dietary factors and biomarkers of cell proliferation; determine the efficacy and safety of long-term (5 years) repeat colonoscopy in patients with small polyps.

Condition	Treatment or Intervention	Phase
large (>1 cm) adenomas Colorectal Cancer	Procedure: Colonoscopy	Phase III

Further Study Details: 

Expected Total Enrollment:  3000

Primary Hypothesis: Risk factors can be determined for large (>1 cm) adenomas, precursor lesions for colorectal cancer. Secondary Hypothesis: Determine long-term rates for development or recurrence of polyps; determine sensitivity/specificity of current colon cancer screening strategies; determine relationship of dietary factors and biomarkers of cell proliferation; determine the efficacy and safety of long-term (5 years) repeat colonoscopy in patients with small polyps.

Intervention: Phase I: All patients undergo full colonoscopy. Phase II: Randomization to repeat colonoscopy at 2-3 years and 5 years after baseline, or, repeat colonoscopy at 5 years only. Phase III: Ten-year follow-up on all Phase I patients for medical outcomes. Repeat colonoscopy at 10 years on polyp-free patients (Phase I) aged 50-64.

Primary Outcomes: Presence of risk factors and adenomatous polyps including prevalence, descriptive characteristics, and long-term occurrence/recurrence rates.

Study Abstract: Phase I is a cross-sectional study designed to identify risk factors for large (>1 cm) adenomatous polyps. Approximately 3200 asymptomatic subjects (age 50-75) have completed risk factor assessment, medical and dietary histories, and have undergone complete colonoscopy examination. This will identify for comparison purposes a polyp-free control group and is the first large prospective study to include such a group. Data at colonoscopy will characterize the prevalence, size and distribution of adenomatous polyps. This will permit an assessment of sensitivity of sigmoidoscopy in this population. In addition, tissue from normal rectal mucosa will be analyzed for evidence of cell proliferation activity. The primary focus of Phase I is a risk factor analysis. A multivariate analysis will be performed to determine the relationship of historical and environmental factors as well as cell proliferation activity with the presence of adenomatous polyps. A cohort consisting of a subgroup of polyp patients (large and small) and matched polyp-free controls will be tracked longitudinally to determine polyp occurrence/recurrence rates.

Phase II of the study is a long-term follow-up study designed to evaluate the relative risk of two repeat colonoscopy schedules for patients with small polyps identified in Phase I of the study. Recruitment is complete with 615 patients eligible (of the target 808) assigned at random to either repeat colonoscopy at 2-3 years and 5 years, or to repeat colonoscopy at 5 years only. This phase will also provide preliminary longitudinal risk factor information related to occurrence/recurrence of polyps.

Phase III was recently approved for 5-year extension of follow-up period. All Phase I patients will be reconsented to provide medical outcome data for a period of 10 years from baseline exam. Phase I patients polyp-free, aged 50-64 will be offered repeat colonoscopy at 10 years to evaluate long-term risk.

Results (Phase I): 3121 patients had complete colonoscopy which revealed high rates of neoplasia: 37.5% had one or more neoplastic lesions; 10.5% had advanced neoplasia including 30 cases of invasive cancer (1%). There were 3.7% of patients with no lesions in the rectum or sigmoid colon who had advanced neoplasia elsewhere in the colon: 32% of all patients with advanced neoplasia would not be detected with an exam of the rectum or sigmoid colon (distal); 62% of patients with proximal advanced neoplasia would not be detected with an exam of the rectum and sigmoid colon. There were few serious complications (0.3%).

The one-time fecal occult blood test (FOBT) was evaluated as a diagnostic test for advanced neoplasia. A positive FOBT indicated an increased likelihood (3-4x) of advanced neoplasia. However, one-time FOBT failed to detect 75% of patients with advanced neoplasia.

The primary analysis of risk factors is currently being completed.

Ages Eligible for Study:  50 Years   -   75 Years,  Genders Eligible for Study:  Both

Criteria

Patients with large (>1 cm) adenomas or Colorectal Cancer

Arizona
      Vamc - Phoenix, Az, Phoenix,  Arizona,  United States
      Vamc - Tucson, Az, Tucson,  Arizona,  United States
      Vamc - Tucson, Az, Tucson,  Arizona,  United States
California
      Vamc - Long Beach, Ca, Long Beach,  California,  United States
      Vamc - Palo Alto, Ca, Palo Alto,  California,  United States
      Vamc - San Francisco, Ca, San Francisco,  California,  United States
Colorado
      Vamc - Denver, Co, Denver,  Colorado,  United States
Illinois
      Vamc - Hines, Il, Hines,  Illinois,  United States
      Vamc - Hines, Il, Hines,  Illinois,  United States
Minnesota
      Vamc - Minneapolis, Mn, Minneapolis,  Minnesota,  United States
      Vamc - Minneapolis, Mn, Minneapolis,  Minnesota,  United States
Missouri
      Vamc - Kansas City, Mo, Kansas City,  Missouri,  United States
North Carolina
      Vamc - Durham, Nc, Durham,  North Carolina,  United States
Oregon
      Vamc - Portland, Or, Portland,  Oregon,  United States
Texas
      Vamc - Dallas, Tx, Dallas,  Texas,  United States
Vermont
      Vamc - White River Jct.,Vt, WHITE RIVER JCT.,  Vermont,  United States

Study ID Numbers:  380
Record last reviewed:  August 2004
Last Updated:  October 13, 2004
Record first received:  March 18, 2002
ClinicalTrials.gov Identifier:  NCT00032344
Health Authority: United States: Federal Government
ClinicalTrials.gov processed this record on 2005-04-08