Association between Seminal Vesicle Invasion and Prostate Cancer Detection Location after Transrectal Systemic Biopsy among Men Who Underwent Radical Prostatectomy

Abstract

Background: Our hypothesis is that the location of the seminal vesicles near the base of the prostate, the more positive cores are detected in the base, the greater the risk of seminal vesicle invasion. Therefore we investigate the clinical outcomes of base dominant prostate cancer (BDPC) in transrectal ultrasound (TRUS) -guided biopsies compared with anteromiddle dominant prostate cancer (AMPC).

Methods: From November 2003 to June 2014, a total of 990 intermediate and high risk prostate cancer (PCa) patients who underwent radical prostatectomy (RP) were enrolled and stratified into two groups according to proportion of positive cores-BDPC group had ≥ 33.3% ratio of positive cores from the prostate base among all positive cores and AMPC group < 33.3% in systemic biopsy. Between two groups, we compared the rate of pathologic outcomes and biochemical recurrence (BCR). We performed multivariate logistic regression model to confirm the significance of BDPC to seminal vesicle invasion (SVI) and Cox proportional hazard analysis to BCR.

Results: Among these 990 PCa patients, the 487 patients in BDPC group had more advanced clinical stage (p<0.001), a higher biopsy GS (p = 0.002), and a higher rate of extracapsular extension (ECE), SVI and BCR (all p<0.001) than AMPC group. The patients in BDPC group had poor BCR free survival rate via Kaplan-meier analysis (p<0.001). The ratio of the base positive cores was a significant predictor to SVI in multivariate analysis (p < 0.001) and significant predictor of BCR in multivariate Cox proportional analysis (hazard ratio: 1.466, p = 0.004).

Conclusions: BDPC in TRUS-guided prostate biopsies was significantly associated with SVI and BCR after adjusting for other clinical factors. Therefore, BDPC should be considered to be a more aggressive tumor despite an otherwise similar cancer profile.

Fig 1. Kaplan-Meier survival curve of biochemical recurrence-free survival according to ratio of base cores.

The 5-year BCR-free survival was 60.7% in the base dominant prostate cancer group compared with 74.6% in the anteromiddle dominant prostate cancer group (log rank test, p-value = 0.001).

Fig 2

Kaplan-Meier survival curve of biochemical recurrence-free survival according to ratio of base cores (A) among patient with biopsy Gleason score 7 (log rank test, p-value = 0.074) and (B) among patients with biopsy Gleason score 8–10 (log rank test, p-value = 0.004).