Immunohistochemical evaluation of cathepsin D expression in colorectal cancer

Determination of cathepsin D has been proven to be prognostically relevant in breast cancer. Cathepsin D, a lysosomal proteinase, is suggested to be causally involved in tumor invasion. In this study we investigated cathepsin D expression immunohistochemically in 106 colorectal adenocarcinomas with the intention to evaluate its prognostic significance in this type of cancer. The majority of colorectal adenocarcinomas (93/106) stained positive for cathepsin D, while normal colon was almost completely negative. A trend toward stronger staining intensity was found in Dukes' stage C and D tumors (p < 0.1), but cathepsin D expression was found to have no influence on survival in this tumor type nor did it correlate with other known prognostic factors, e.g., histological differentiation, lymph vessel invasion, or rate of proliferation. Staining of lymph node metastases did not differ significantly from that of their primary tumors. Stronger staining intensity of tumor tissue in the neighborhood of inflammatory cells may be due to paracrine activation.