Prognostic significance of positive surgical margins in patients with extraprostatic carcinoma after radical prostatectomy

Abstract

Background: A significant number of prostate adenocarcinoma patients undergoing radical prostatectomy are found to have microscopic extraprostatic disease extension. A majority of these patients have focal extraprostatic extension limited to one or both sides of the prostate. In addition, positive surgical margins are a common pathologic finding in this patient subgroup. In the current study, the authors evaluated the impact of positive surgical margins as an independent predictive factor for prostate specific antigen (PSA) progression in patients with pT3a/b N0M0 carcinoma.

Methods: The Mayo Clinic prostate cancer registry list provided 1202 patients with pT3a/b NO prostate carcinoma (no seminal vesicle or regional lymph node involvement) who underwent a radical prostatectomy between 1987-1995. To reduce confounding variables, patients who received preoperative therapy or adjuvant therapy were excluded, resulting in 842 patients who were eligible for analysis.

Results: A total of 354 patients (42%) had > or = 1 positive surgical margins whereas 488 patients (58%) demonstrated no margin involvement. The sites of margin positivity were as follows: apex (n = 163), base (n = 47), posterior prostate (n = 227), and anterior prostate (n = 11). A total of 111 patients had > or = 2 positive surgical margins. The 5-year survival free of clinical recurrence and/or biochemical failure (postoperative PSA level > 0.2 ng/mL) for patients with no positive surgical margins was 76% and was 65% for patients with 1 positive surgical margin (P = 0.0001). There was no significant difference in biochemical disease progression between patients with 1 versus those with > or = 2 surgical margins (65% vs. 62%). Multivariate analysis revealed that positive surgical margins were a significant predictor (P = 0.0017) of clinical disease recurrence and biochemical failure (relative risk, 1.55; 95% confidence interval, 1.18-2.04) after controlling for preoperative PSA, Gleason score, and DNA ploidy.

Conclusions: In the current study, positive surgical margins were found to be a significant predictor of disease recurrence in patients with pT3a/b NO prostate carcinoma, a finding that is independent of PSA, Gleason score, and DNA ploidy. The benefit of adjuvant therapy in optimizing recurrence-free survival remains to be tested.