PROLIFERATING CELL NUCLEAR ANTIGEN EXPRESSION AT THE INVASIVE TUMOR MARGIN PREDICTS MALIGNANT POTENTIAL OF COLORECTAL CARCINOMAS

Background. Proliferative activity may be a useful measure of malignan t potential for a variety of tumors. Colorectal carcinomas contain mul tiple cell populations with different biologic properties. The invasiv e tumor margin is thought to represent the area with the highest metas tatic potential. Methods. Cell proliferation at the invasive tumor mar gin of 49 specimens of advanced colorectal carcinoma was assessed by i mmunohistochemical staining of proliferating cell nuclear antigen (PCN A) and compared with clinicopathologic findings. Results. Colorectal c arcinomas showed a wide range of PCNA labeling indexes (LI), reflectin g variation in proliferative activity. The PCNA LI of tumors showing v enous invasion (mean, 51.7% +/- 16.2%) was significantly higher than t hat of tumors without venous invasion (mean, 36.7% +/- 18.2%; P < 0.01 ). A strong association was observed between the PCNA LI and the metas tatic potential of colorectal carcinoma; the PCNA LI of tumors showing lymph node metastasis (mean, 50.5% +/- 17%) was significantly higher than that of tumors without nodal involvement (mean, 39.8% +/- 18.5%; P < 0.05). In addition, the PCNA LI of tumors metastatic to liver (mea n, 55.2% +/- 15.7%) was significantly higher than that of tumors witho ut liver metastasis (mean, 41.0% +/- 17.6%; P < 0.01). Correlation wit h histologic features at the invasive tumor margin showed that a highe r PCNA LI was associated with less differentiated tumors (P < 0.05). C onclusion. Evaluation of the PCNA LI at the invasive tumor margin may help identify colorectal carcinomas that have a higher malignant poten tial.