Urinary PSA level and relative tumor volume after prostate biopsy

To estimate the ratio between urinary prostate specific antigen (uPSA) and tumor volume after prostate biopsy.

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.

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.

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.