Prospective study on prognostic significance of DNA ploidy and Ki-67 expression in colorectal cancer

The aim of the study is to correlate tumoral DNA ploidy and Ki-67 expression with therapy response, Overall Survival (OS), Disease Specific Survival (DSS) and Disease Free Survival (DFS). Three samples of colorectal cancer were collected from each patient. One sample of normal tissue was our internal control. DNA ploidy was evaluated by FACSCalibur cytometer and Ki-67 by immunohistochemistry. 67 patients were studied and aneuploidy was found in 65.7% of carcinoma with a Ki-67 median expression of 55%. After surgery and chemotherapy in 35% of the patients with aneuploid carcinoma and high proliferative activity (Ki-67>55%) there was no evidence of disease in 100% of patients with DNA diploidy and low proliferative activity (Ki-67<55%). Tumoral aneuploidy significantly correlated with lower OS, DSS and DFS (18% vs 86% at 30 months). Univariated analysis demonstrated a significant correlation between aneuploidy and develop disease progression (p=0,033, odd ratio=5.7), while the cut-off of 55% for Ki-67 expression did not correlate with OS, DSS and DFS. Preliminary results (the study is still in progress) seem to suggest that DNA ploidy has a prognostic and predictive significance in colorectal carcinoma.