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.