Predicting CAP in patients with intermediate PSA using modified PSA indices.

OBJECTIVES: To test a new PSA index: peripheral zone fraction PSA (PSA-PZ) and evaluate its' predictive value in patients with intermediate PSA.

METHODS: Fifty seven of 273 patients with serum PSA 4-10 ng/ml had CAP (21%). Total prostate volume and transition zone volume were calculated. Different cut-off points were used to calculate specificity, sensitivity, efficacy, positive and negative predictive values for PSA, PSAD, PSA-TZ and PSA-PZ (PSA-PZ= serum PSA((Total gland volume-TZ volume)/(Total gland volume))

RESULTS: The distribution of PSA-PZ is presented. PSA-PZ is shown to be effective in DRE negative patients with serum PSA 4-10 ng/ml. For patients with PSA-PZ (1.5 ng/ml the biopsy may be spared with no cancer being missed.

CONCLUSIONS: The mathematical formula for PSA-PZ is straightforward and easy to use. Its application is convenient in the clinical setting. We suggest the use of PSA-PZ mainly in DRE negative patients having large glands and serum PSA between 4-10.