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

The aim of the study was 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. We studied 67 patients and we found aneuploidy in 65,7 percent of carcinoma with a Ki-67 median expression of 55 percent. After surgery and chemotherapy in 35 percent of the patients with aneuploid carcinoma and high proliferative activity (Ki-67 greater than 55 percent) there were no evidence of disease versus 100 percent of patients with DNA diploidy and low proliferative activity (Ki-67 less than 55 percent). Tumoral aneuploidy significantly correlated with lower OS, DSS and DFS (18 percent vs 86 percent 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 percent for Ki-67 expression did not correlate with OS, DSS and DFS. Preliminary results (the study is still in progress) seemed to suggest that DNA ploidy has a prognostic and predictive significance in colorectal carcinoma.