Clinical utility of serine proteases in breast cancer

Abstract

The serine protease uPA and its inhibitor PAI-1 are involved in the degradation of tumor stroma and basement membrane. The independent prognostic value of serine protease urokinase-type plasminogen activator uPA and its inhibitor PAI-1 in breast cancer has been almost uniformly confirmed in numerous individual studies as well as in a meta-analysis, including 18 data sets of more than 8,000 patients. According to these observations, the risk of relapse in node negative patients with low levels of uPA and PAI-1 is less then 10%; these patients could be spared from toxic adjuvant systemic therapy. Clinically relevant and even more important is the information that uPA and its inhibitor PAI-1 may also have a predictive value for response to either hormonal or cytotoxic therapy in early breast cancer. According to our data obtained from altogether 460 operable breast cancer patients, uPA and PAI-1 may have a predictive value for the response to hormone therapy, but not to chemotherapy. The high PAI-1 levels were associated with a higher risk of relapse in the patients without adjuvant systemic therapy (HR 2.14; C.I. 95%= 0.48-9.56; p=0.321) and in the patients treated with chemotherapy (RR 2.48; C.I. 95%= 1.35-4.57; p=0.003). However, in the patients treated with adjuvant hormone therapy, either alone or in combination with chemotherapy, the prognostic value of uPA and PAI-1 was diminished. Moreover, high levels of both uPA and PAI-1 were associated with a lower risk of relapse (HR 0.79; p=0.693 and HR 0.26 p= 0.204, respectively). On the basis of currently available evidence, serine protease uPA and its inhibitor PAI-1 are certainly the markers that improve a proper selection of candidates for adjuvant systemic therapy and may also be the markers that could facilitate treatment decision in each individual patient, which is of utmost importance.