Urinary PSA level and relative tumor volume after prostate biopsy

Abstract

Objectives: To estimate the ratio between urinary prostate specific antigen (uPSA) and tumor volume after prostate biopsy. Methods: From 2000 to July 2008, uPSA concentration was determined in 60 patients with clinically organ-confined prostate cancer (PCa). All patients underwent six-area transrectal ultrasound (TRUS) - guided biopsy, with at least 12 biopsy cores. Single pathologist determined tumor grade (G), Gleason score (GS), the percentage of tumor infiltration (% TI) and the percentage of positive cores (% PC) in all biopsy cores. Additionally, relative tumor-biopsy volume (RTV) was calculated by multiplying % PC, % TI and prostate ultrasound- derived volume (Vol). Forty-one patients underwent retropubic radical prostatectomy (RRP), while 19 patients underwent radiation therapy. Results: Average uPSA was 308.6+311.9 ng/ml (range 0.06-988 ng/ml), average PSA was 9.7+ 5.5 ng/ml (range 1.2-24.3 ng/ml), tumor grade 1.7+ 0.8, Gleason score 5.2 + 1.3, the percentage of tumor infiltration 27.6+21.8 %, and the percentage of positive cores, 52.2+30.7 %. Average RTV was 6.3+ 8.4 ml (0.29-56 ml). All patients were divided in two groups: I, with RTV 4 ml and II, with RTV = 4 ml. The patients with RTV 4 ml had lower G (1.4 0.6 vs. 2.1+0.8, p=0.0002), lower GS (4.5+1 vs. 5.8+1.3, p=0.003) and higher uPSA (389.4+340.8 vs. 193.1 +229.7, p=0.014). There were no differences in serum PSA levels between the groups. Conclusion: Relative tumor-biopsy volume (RTV) is useful parameter in the preoperative assessment of tumor volume. Patients with higher RTV had significantly higher G and GS. However, these patients had significantly lower uPSA. This phenomenon could be the consequence of compromised PSA drainage from the peripheral zone of the prostate, caused by the tumor.