ORIGINALARTICLE : The Expression of Multiple Proteins as Prognostic Factors in Colorectal Cancer ; Cathepsin D, p53, COX-2, Epidermal Growth Factor Receptor, C-erbB-2, and Ki-67

Background/Aims: A single gene mutation alone cannot explain the poor prognosis of colorectal cancer. This study aimed to establish a correlation between the expression of six proteins and the prognosis of colorectal cancer patients. Methods: Tissue samples were collected from 266 patients who underwent surgery for colorectal cancer at our institu-tion from January 2006 to December 2007. The expression of six proteins were determined using immunohistochemi-cal staining of specimens. Results: Cathepsin D, p53, COX-2, epidermal growth factor receptor, c-erbB-2, and Ki-67 expression were detected in 38.7%, 60.9%, 37.6%, 35.7%, 30.1%, and 74.4% of the samples, respectively. The expres-sion of cathepsin D was significantly correlated with reduced cancer-free survival (p=0.036) and colorectal cancer-specific survival (p=0.003), but the other expression levels were not. In a multivariate analysis, cathepsin D expression was found to be an independent prognostic factor for poorer colorectal cancer-specific survival (hazard ratio, 8.55; 95% confidence interval, 1.07 to 68.49). Furthermore, patients with tumors expressing four or more of the proteins had a significantly decreased cancer-free survival rate (p=0.006) and colorectal cancer-specific survival rate (p=0.002). Conclusions: Pa-tients with cathepsin D positivity had a poorer outcome than patients who were cathepsin D-negative. Thus, cathepsin D may provide an indicator for appropriate intensive follow-up and adjuvant chemotherapy.