Prostate volume and the incidence of extraprostatic extension: Is there a relation?

Background and Purpose: Extraprostatic extension (EPE) of tumor is an important prognostic indicator that has an impact on long-term survival after radical prostatectomy. We investigated whether the prostate size has any association with the tumor volume and the incidence of EPE. Patients and Methods: Seven hundred consecutive robot-assisted radical prostatectomy procedures performed by a single surgeon at a single center were studied. Preoperative parameters (demographic details, prostate-specific antigen (PSA) level, biopsy characteristics, and tumor volume) and the postoperative histopathologic details of the specimen (prostate volume, Gleason sum, EPE, and surgical margin status) were compared among the small prostate (< 40cc), intermediate size (40-70cc), and large prostate (>70cc) groups. Chi-square analysis was performed for comparison of groups with nominal variables while continuous variables were compared using analysis of variance. A double-sided P value of less than 0.05 was considered statistically significant. Results: A greater proportion of patients in the large prostate group had T _1c tumor compared with those in the small prostate group (90.2% v 78.3%). Younger men and smaller prostates had lower preoperative PSA levels (P< 0.001). A significantly higher PSA density (0.16 v 0.07) and cancer density (0.0102 v 0.0025), however, was observed in patients with small prostates compared with those with large prostates. A total of 102 (14.6%) patients had EPE on the final pathologic analysis while 8.6% of the patients had positive surgical margins. Greater incidence of EPE was observed in the group with smaller prostates compared to those in the large prostate group (16.7% v 7.3%). Conclusion: Small prostates have a higher cancer density and a greater incidence of EPE of tumor.