Osteopontin plasma level does not detect prostate cancer in patients referred for diagnostic prostate biopsy

Prostate cancer is the second most frequent cause of tumor-related deaths in men in Western countries. The selection and evaluation of new markers might help to overcome the limits of the most widely used diagnostic tool, the prostate-specific antigen (PSA) test, often combined with digital rectal examination (DRE). Osteopontin (OPN) is an integrin-binding glycoprotein that has recently been shown to be related to tumor development, progression and metastasis in both experimental and clinical studies. The present study compares plasma OPN levels and tumor presence and grade in a group of PSA/DRE-positive patients referred for diagnostic prostate biopsy. Plasma OPN levels were measured by enzyme-linked immunosorbent assay in blood samples of 194 PSA/DRE-positive patients referred for diagnostic prostate biopsy. OPN measurements were compared with PSA levels and tumor presence and grade as established by needle biopsy. Plasma OPN levels were not increased in patients with prostate cancer, and in patients with high-grade prostate cancer the plasma OPN levels were not different from those in patients with low-grade or no prostate cancer. In PSA/DRE-positive patients referred for diagnostic prostate biopsy, OPN does not appear to be a plasma marker able to detect prostate cancer or high-grade prostate cancer.