About Urokinase Plasminogen Activator (uPA)
Urokinase is an enzyme that occurs naturally in your urine and blood plasma. It is produced in your kidneys, and helps dissolve blood clots in your kidneys or bladder. Tumors can also produce urokinase, and researchers think that it may encourage tumor cells to spread. Plasminogen is a substance that, when activated, becomes plasmin, an enzyme that digests fibrin, an insoluble protein that forms when your blood clots.
PAI-1 Inhibits uPA
Plasminogen activator inhibitor 1 (PAI-1) is a special protein that inhibits urokinase. If the levels of PAI-1 and uPA are both high, it may mean that your tumor is overproducing urokinase, allowing cancer cells to spread beyond the tumor. Your high levels of PAI-1 may not be able to inhibit the growth of the cancer without additional help from chemotherapy.
What Are the Benefits of a uPA and PAI-1 Tumor Marker Test?
If your lymph nodes are clear of cancer cells (node-negative), and your tumor is hormone sensitive, low levels of uPA and PAI-1 may indicate that your risk of recurrence is quite low. In this case, chemotherapy would not improve your survival, or if you opt for chemo, your survival will be improved by only a small percent. If you have high levels of uPA and PAI-1, your risk of recurrence is high, and chemotherapy would benefit you. A treatment plan that includes cyclophosphamide, methotrexate, and 5-fluorouracil (CMF) chemotherapy would improve your survival chances.
Sources:
American Society of Clinical Oncology. ASCO Patient Guide: Tumor Markers for Breast Cancer. Last Updated: October 22, 2007.
