Influence of preoperative core biopsies on uPA/PAI-1 expression in breast cancer tissue

The urokinase-type plasminogen activator (uPA) and the plasminogen activator inhibitor-1 (PAI-1) are involved in tumor invasion and metastasis as well as wound healing and inflammation. We investigated the impact of tissue injury by preoperative sampling on the level of uPA/PAI-1 in paraffin tissue of 55 breast cancer cases by immunohistochemistry. The tumor area surrounding the biopsy channel was compared with distant intact tumor tissue. uPA and PAI-1 were constantly expressed by the tumor cells. Fibroblastic expression was higher in the tumor area surrounding the biopsy channel than in intact tissue with 47 vs 29 positive cases for uPA (p<0.001) and 35 vs 25 positive cases for PAI-1 (p=0.055). A decrease in fibroblastic enzyme expression from the biopsy area to the intact tumor tissue was seen in 21 cases for uPA and 16 cases for PAI-1. This difference was most evident in cases with an interval of 6 days and longer between biopsy and surgery. In conclusion, fibroblastic inflammatory reaction around the biopsy channel affects stromal uPA and PAI-1 expression, which possibly leads to falsely increased enzyme levels in ELISA. Tissue specimen for ELISA analysis should not be taken from the tumor area around the biopsy channel in the resection specimen.