[A single positive prostatic biopsy out of six systematic biopsies is not correlated with the intracapsular nature of the tumor on an individual level].

Objective: To evaluate whether or not a single positive prostatic biopsy out of six systematic ultrasound-guided biopsies, is reliably correlated manner with favourable histopathological features of the tumour on the radical prostatectomy (RP) specimen.

Materials And Methods: In a series of 158 patients undergoing RP for clinically localized prostatic cancer, 15.2% had only one positive biopsy out of 6 systematic biopsies. We compared the rates of capsular effraction (C+) and positive resection margins (RM+), assessed on the operative specimen, in this group of patients with a single positive biopsy (group 1) and in the group (group 2) diagnosed by more than one positive biopsy. The postoperative biological progression rate (P+), defined as an immediate or secondary postoperative elevation of PSA beyond 0.1 ng/ml by polyclonal assay, was also evaluated in the two groups. The Gleason score was evaluated and compared on biopsies and on RP specimens.

Results: 29.2 of cases were C+, 16.7% were RM+ and 26% were P+ in group 1, versus 70%, 46.5% and 49.5%, respectively, in group 2. All differences were statistically significant. All patients in group 1 with less than 10% of prostatic tissue invaded on the positive biopsy had stage P2, while all patients with 100% of the length of the biopsy invaded by tumour had stage P3. The Gleason score was accurately predicted by the positive biopsy in 39% of cases and was underestimated in 39% of cases.

Conclusion: A single positive prostatic biopsy out of six systematic biopsies is a useful predictive factor of local extension, but, in the individual patient, does not guarantee favourable histopathological characteristics of the tumour, nor a favourable course of the disease.