Differential PCNA Expression Between Neoplastic and Adjacent Mucosa as a Prognostic Marker in Colorectal Adenoma-Carcinoma Progression

Background/Aim: The prognostic significance of proliferating cell nuclear antigen (PCNA) has not yet been defined in either colorectal adenoma or carcinoma. This study aimed to compare the differences in PCNA expression between pathologically altered tissue (polyp, adenoma, carcinoma) and the surrounding tissue (termed PCNA expression difference, PCNA-ED) as a potential prognostic marker in colorectal tumor progression. Patients and Methods: Tissue specimens used for this study were obtained from 63 non-neoplastic epithelial polyps, 211 colorectal adenomas, and 156 colorectal adenocarcinomas, as well as adjacent normal mucosa. Results: PCNA-ED was absent in non-neoplastic polyps, present in 13.7% of adenomas, and significantly more frequent in adenocarcinomas (33.3%). Higher PCNA-ED correlated with increasing adenoma size, grade of dysplasia, depth of invasion, and Dukes staging. High PCNA-ED was significantly associated with early recurrence, lymphovascular invasion, liver metastases, and reduced survival. Among patients with Astler-Coller B2 tumors, high PCNA-ED suggested a need for adjuvant chemotherapy. Conclusion: PCNA-ED is strongly associated with malignant transformation, recurrence, and adverse prognosis in colorectal neoplasms. Its measurement may offer valuable prognostic insight and inform postoperative management strategies.