A Pilot Study of DNA Aneuploidy in Colorectal Adenomas and Risk of Adenoma Recurrence1

This case-control study examined whether DNA aneuploidy in colorectal adenomas is a risk factor for subsequent ademona recurrence. Cases (recurrent polyp formers) were defined as persons with diagnoses of new adenomas at 2 colonoscopies following the index (first) adenoma diagnosis; controls were persons with no new adenomas at a follow-up at least 1 year after the index diagnosis. Cases (n = 22) and up to 3 controls (n 29) were matched for factors known to be associated with polyp recurrence or aneuploidy: (a) age; (b) histology; (c) number of index polyps; and (d) size of largest index polyp. The largest adenoma from the index colonoscopy was removed from the paraffin block and analyzed for DNA content abnormalities by flow cytometry. On the basis of the observed distribution of aneuploidy in casecontrol sets, the point estimate for the relative odds of recurrence given aneuoploidy in the index polyp was infinity (P < 0.035), and the lower bound for the 95% confidence interval was 2.02. We conclude that in this convenience sample, DNA aneuploidy increased the risk of recurrent colorectal adenomas. Larger, preferably prospective studies are needed before DNA content flow cytometric analysis of colorectal adenomas can be recommended as a routine clinical practice, but these results do suggest that polyp ploidy should be assessed in research studies using adenomas as end points or intermediate end point markers.