ASPO Abstracts
Changes in Colorectal Polyps Over Two Decades: Secondary Analyses of Clinical Trial Data
Category: Early Detection & Risk Prediction
Conference Year: 2020
Abstract Body:
Introduction
Colorectal cancer is the third most common cancer in the United States among men and
women combined. Screening methods like colonoscopy have allowed for early detection of
colorectal polyps before they develop into cancer, and several clinical trials have been
conducted to test methods of colorectal cancer prevention by reducing polyp formation. These
studies have included Wheat Bran Fiber (WBF) trial, Ursodeoxycholic Acid (UDCA), and
Selenium (SEL). The purpose of the present study was to determine if there were significant
changes in colorectal polyp characteristics across the baseline measurements of these three
clinical trials.
Methods
This study is a secondary analysis of data collected from 4257 participants from the WBF,
UDCA, and SEL trials. The primary outcome was a difference in polyp characteristics across
the baseline measurements of the three trials as measured by the number of adenomas
present at the baseline colonoscopy, and the size and location of those adenomas, and the
presence of multiple adenomas. This approach allows for an understanding of whether the type
of adenomas detected by colonoscopy have shifted over time.
Results
Our results indicate that there was a statistically significant difference in the characteristics of
colorectal polyps across baseline measurements of the three clinical trials. The proportion of
individuals with 3+ adenomas found at the time of baseline colonoscopy has statistically
significantly increased over time, with a proportion of 12.2%, 13.9%, and 18.5% for WBF,
UDCA, and SEL, respectively (p<0.0001). Baseline adenoma size (mm) also differed
significantly over time, with larger adenomas detected in WBF (8.29 + 5.88) and UDCA (8.90 +
5.87) as compared to SEL (7.83 + 5.53; p <0.0001).
Conclusion
These findings suggest that there were significant differences in the size and the proportion of
multiple occurrences of colorectal polyps across the baseline measures in three clinical trials
that randomized participants from 1990 to 2011. These findings were not attenuated by
controlling for age or body mass index. Further research is needed to understand the apparent
shifts in adenoma characteristics over time.
Keywords: Clinical trial, colorectal cancer, cancer epidemiology