The Polyp Prevention Trial I: Rationale, design, recruitment, and baseline participant characteristics Journal Article
| Authors: | Schatzkin, A.; Lanza, E.; Freedman, L. S.; Tangrea, J.; Cooper, M. R.; Marshall, J. R.; Murphy, P. A.; Selby, J. V.; Shike, M.; Schade, R. R.; Burt, R. W.; Kikendall, J. W.; Cahill, J.; for the PPT Study Group |
| Contributors: | Winawer, S.; Bloch, A.; Mayer, J.; Morse, R.; Latkany, L.; D'Amato, D.; Schaffer, A.; Cohen, L. |
| Article Title: | The Polyp Prevention Trial I: Rationale, design, recruitment, and baseline participant characteristics |
| Abstract: | The Polyp Prevention Trial (PPT) is a multicenter randomized controlled trial examining the effect of a low-fat (20% of total energy intake), high- fiber (18 g/1000 kcal), high-vegetable and -fruit (5-8 daily servings) dietary pattern on the recurrence of adenomatous polyps of the large bowel, precursors of most colorectal malignancies. Eligibility criteria include one or more adenomas removed within 6 months of randomization; complete nonsurgical polyp removal and complete colonic examination to the cecum at the qualifying colonoscopy; age 35 years or more; no history of colorectal cancer, inflammatory bowel disease, or large bowel resection; and satisfactory completion of a food frequency questionnaire and 4-day food record. Of approximately 38,277 potential participants with one or more polyps recently resected, investigators at eight clinical centers randomized 2,079 (5.4%; 1,037 in the intervention and 1,042 in the control arm) between June 1991 and January 1994, making the PPT the largest adenoma recurrence trial ever conducted. Of PPT participants, 35% are women and 10% are minorities. At study entry, participants averaged 61.4 years of age; 14% of them smoked, and 22% used aspirin. At the baseline colonoscopy, 35% of participants had two or more adenomas, and 29% had at least one large (≥1 cm) adenoma. Demographic, behavioral, dietary, and clinical characteristics are comparable across the two study arms. Participants have repeat colonoscopies after 1 (T1) and 4 (T4) years of follow-up. The primary end point is adenoma recurrence; secondary end points include number, size, location, and histology of adenomas. All resected lesions are reviewed centrally by gastrointestinal pathologists. The trial provides 90% power to detect a reduction of 24% in the annual adenoma recurrence rate. The primary analytic period, on which sample size calculations were based, is 3 years (T1 to T4), which permits a 1-year lag time for the intervention to work and allows a more definitive clearing of lesions at T1, given that at least 10-15% of polyps may he missed at baseline. The final (T4) colonoscopies are expected to be completed in early 1998. |
| Keywords: | adult; middle aged; clinical trial; cancer recurrence; patient selection; research design; follow-up studies; caloric intake; energy intake; demography; cancer prevention; neoplasm recurrence, local; colonic neoplasms; smoking; adenoma; colonoscopy; fruit; vegetable; vegetables; phase 1 clinical trial; dietary intake; colonic polyps; polyp; colon carcinogenesis; sample size; precancerous conditions; minority groups; adenomatous polyps; aspirin; low fat diet; diet, fat-restricted; dietary fiber; intervention studies; humans; human; male; female; priority journal; article |
| Journal Title: | Cancer Epidemiology Biomarkers and Prevention |
| Volume: | 5 |
| Issue: | 5 |
| ISSN: | 1055-9965 |
| Publisher: | American Association for Cancer Research |
| Date Published: | 1996-05-01 |
| Start Page: | 375 |
| End Page: | 383 |
| Language: | English |
| PUBMED: | 9162304 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | Article -- Export Date: 22 November 2017 -- Source: Scopus |
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