New indicator for prostate gland biopsy when malignancy is in question.

The aim of our study was to find out a new indicator with a higher specificity level than prostate prostate-specific antigen (PSA) in order to achieve a better selection of patients who will undergo prostate biopsy. Trans-rectal ultrasound-guided prostate biopsy was performed in 135 patients who had elevated PSA level and/or palpable nodule on digital rectal examination. The PSA level was ≤ 10 ng/mL in 81 patients and >10 ng/mL in 54 patients. We designed a new formula consisting of prostate volume, patient's age, and free prostate specific antigen. Its resultant was defined as prostate biopsy index and was compared with the most currently used parameters. Histology results yielded prostate gland malignancy in 40 (30%) patients. Our new index differed significantly between the malignant and the non-malignant patient categories (P = 0.01). The ROC curve analysis at different specificity and sensitivity levels (85%, 90% and 95%) and regarding the area under the curve (AUC), our new index was significantly better than the other studied parameters (P = 0.001). Additionally, the AUC in patients with a PSA level ≤ 10 ng/mL and between 10.1 and 20 ng/mL was 0.75 and 0.78, with a sensitivity of 91% and 83% and a specificity of 24% and 73%, respectively, at a cut-off point of 1.7. The overall sensitivity and specificity at the same point were 80% and 41%, respectively. In conclusion, the performance of our new index was superior to all other evaluated parameters. At 83% sensitivity with a cut-off point of 1.7, 63.5% of the performed biopsies could have been avoided in patients with a PSA level between 10.1 and 20 ng/mL.