Proliferative activity in colonic adenomas as a predictor of metachronous adenomas as assessed by proliferating cell nuclear antigen immunohistochemistry.

OBJECTIVES

The aim of this study was to determine whether cell proliferation in colonic adenomas, as estimated by proliferating cell nuclear antigen (PCNA), predicts the development of metachronous colonic adenomas.

METHODS

Forty patients who underwent prior endoscopic polypectomy for colonic adenomas were reevaluated by colonoscopy 2 yr later. The expression of PCNA was studied in all adenomas that were removed. A five-point semiquantitative scale of 1-5 was used to estimate the PCNA score by the percentage of positively stained cells.

RESULTS

Among the 40 patients studied, 16 developed recurrent adenomas (group A) and 24 were free of adenomas (group B). At initial colonoscopy, a total number of 51 adenomas (25 in group A and 26 in group B), were found. The median PCNA score in group A and group B index adenomas was 4 (interquartile range, 3-5) and 2 (interquartile range, 1-3), respectively (p < 0.01, Mann-Whitney U-test). A stepwise logistic regression analysis showed that PCNA score is a significant risk factor (p = 0.007, odds ratio 15.8, 95% confidence interval 2.2-112.4) in predicting adenoma recurrence. The median PCNA score in metachronous adenomas was 2 (interquartile range, 1-3). The difference in the PCNA score between group A index and metachronous adenomas was again statistically significant (p < 0.01, Mann-Whitney U-test).

CONCLUSIONS

We conclude that the increased expression of PCNA in colonic adenomas may be a predictor for metachronous adenomas.