ABSTRACT
OBJECTIVES: Ultrasound guided prostate biopsy is the most effective test for prostate cancer diagnosis, but its sensitivity is not higher than 80% so that biopsy repetition must be considered in patients with persistent diagnostic doubts after a previous negative one. However, the majority will be negative as it happened in the first biopsy and the percentage of normal biopsies increases successively. Various indexes based on PSA are proposed to determine which patients have a higher risk of cancer detection by biopsy. We evaluate the efficacy of PSA density (PSAD), free/total PSA ratio (F/T PSA) and PSA velocity (PSAV) to select patients with high PSA and previous negative biopsy. METHODS: 546 patients who underwent more than one prostate biopsy were included in the study. 121 patients underwent 3 biopsies, 25 underwent 4 biopsies and 7 five biopsies, for a total of 1245 biopsies. Patients already diagnosed of prostate cancer who had received treatment, and postoperative urethrovesical anastomosis biopsies were excluded. Between 4 and 6 samples were obtained; transitional zone was included if previous biopsy was negative; sextant biopsy was repeated in high grade PIN, and 4 or 5 cores were taken from the affected side in cases with non conclusive glandular atypia. The relationship between PSAD, PSAV and F/T PSA and the diagnosis of cancer was evaluated, as well as its sensitivity, specificity, positive and negative predictive values. RESULTS: 21.2% patients presented cancer on 2nd biopsy and 26% overall. Mean age was 68.3 years (51-84). Patients with cancer and negative biopsy showed significant differences in F/T PSA and PSAD, but not in PSAV. Sensitivities for PSAD higher than 0.15 ng/ml/ml, F/T PSA lower than 0.18 and PSAV higher than 0.75 ng/ml/year were 0.89, 0.9 and 0.49 respectively and specificities were 0.28, 0.2 and 0.4 respectively. ROC curve areas were calculated for these indexes being 0.63 for F/T PSA, and 0.47 for PSAV. CONCLUSIONS: Although their specificity is low, free to total PSA ratio and PSA density showed the highest sensitivity; PSAV is almost non valid to discriminate the result in the biopsy. Although we could slightly diminish the number of repeat biopsies loosing a few tumors, only the urologist can determine when biopsies should be repeated in patients with elevated PSA, taking into consideration all concurrent factors (Baseline status, age, risk-benefit ratio of new biopsies...).
