Free to total prostatic specific antigen ratio as a new diagnostic tool in prostatic carcinoma.

One hundred seventy-one patients with clinical suspicion of prostate cancer were initially selected and underwent total and free PSA determination, digital rectal examination and transrectal ultrasonography. Sixty-five had total PSA values between 4 to 20 ng/ml. In these patients in addition to the free to total PSA ratio, the sensitivity, specificity, positive predictive value, true and false negative predictive value were evaluated, comparing these findings with histopathological characterization. Receiver Operating Characteristic Analysis was also performed. No statistically significant differences were evidenced between benign and neoplastic prostates comparing total PSA values, while significant differences were found by comparing both free PSA and the free to total PSA ratio (p < 0.01). Our experience demonstrates that using a 0.20 free to total PSA ratio cut-off, it is possible avoid 44.4% of following clinical tests, and biopsies could be saved in almost 40% of patients with a considerable cost-benefit ratio.