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 prolif eration in colonic adenomas, as estimated by proliferating cell nuclea r antigen (PCNA), predicts the development of metachronous colonic ade nomas. Methods: Forty patients who underwent prior endoscopic polypect omy for colonic adenomas were reevaluated by colonoscopy 2 yr later. T he expression of PCNA was studied in all adenomas that were removed. A five-point semiquantitative scale of 1-5 was used to estimate the PCN A 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 n umber of 51 adenomas (25 in group A and 26 in group B), were found. Th e median PCNA score in group A and group B index adenomas was 4 (inter quartile 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 r ecurrence. The median PCNA score in metachronous adenomas was 2 (inter quartile 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 incre ased expression of PCNA in colonic adenomas may be a predictor for met achronous adenomas.