Diagnosis and Prognosis of Prostate Cancer from Circulating Matrix Metalloproteinases and Inhibitors

Although prostate cancer (PCa) is the sixth most common type of neoplasm in the world and the second in prevalence among men (10% of all cases), there is shortage of studies focused on primary prevention of the disorder as well as little understanding on its pathophysiology. Currently, the PCa screening tools are the prostate specific antigen (PSA) dosage conjugated to rectal examination and confirmed by prostate biopsy. Despite the name, the PSA presents reduced specificity, being necessary the identification of new biomarkers that allow an earlier and more precise diagnosis and even better prognosis. Several studies have associated matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) to PCa tumorigenesis and metastasis. Most of the studies so far have been carried out by investigating in situ expression of the metalloproteinases, either by transcriptional measures or by immunohistochemistry with biopsy or postoperative tissue. Investigations in human plasma and serum are scarce, and a bibliographical search resulted in 17 studies which are presented and interpreted herein. This narrative review discusses their settings and findings along with aspects related to circulating metalloproteinases as potential biomarkers for diagnosis or prognosis of the prostatic malignancy, expressing the authors' reticent view on their applicability due to the poor quality of evidence available.